Natural Enemies in Your Garden - Michigan Water Stewardship

Natural Enemies in Your Garden:A Homeowner’s Guideto Biological Control

MICHIGAN STATEU N I V E R S I T Y

EXTENSION

E x t e n s i o n B u l l e t i n 2 7 1 9 , N e w , O c t o b e r 2 0 0 0

Cover Photos

Front cover, clockwise from top left

• Ladybug larva, Coccinella septempunctata (USDA).• Green lacewing adult (Karim Maredia).• Ladybug, Hippodammia parenthesis1.

• Tachinid fly adult (Dave Smitley).

Back cover, from top

• Tomato hornworm covered with braconid parasitoid cocoons1.• Carabid beetle adult, Calosoma spp. (Dave Smitley).

• Virus infected cabbage looper1.

Text Illustrations

• Pages 21 ‘Orius’, 23, 25, 26, 28, 29, 32, 33, 35, 38, 44-46, and 48(Michelle Schwengel, Midwest Biological Control News).

• Pages 15-20, 21 ‘true bug’, 24, 33, 36, 40, and 42 (Jana Lee).• Page 29 ‘Multicolored Asian lady beetle’ (William F. Lyon, O.S.U. Extension

factsheet HYG-215-94: Multicolored Asian lady beetle).• Page 37 (J.J. Culver, 1919, USDA Bulletin 766, plate 1).

• Page 47 (P. Berry, 1938, USDA Circular 485).• Pages 34, 411.

1 (Michael P. Hoffman and Anne C. Frodsham, 1993,“Natural Enemies of Vegetable Insect Pests”, Cornell University).

Natural Enemies in Your Garden:A Homeowner’s Guideto Biological Control

Jana C. LeeDouglas A. Landis

Department of EntomologyMichigan State University

MICHIGAN STATEU N I V E R S I T Y

EXTENSIONMICHIGAN AGRICULTURAL EXPERIMENT STATION

This publication is a product of the Michigan State University Biological ControlProgram within the Center for Integrated Plant Systems. Funding was provided

by the Michigan Agricultural Experiment Station, Project GREEEN and Michigan State University Extension.

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Introduction

Who are Our Friends in the Garden?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Making Biological Control Work for Us . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Conserving Natural Enemies

Conservation Step 1: Don't Reach for the Pesticide Spray . . . . . . . . . . . . . . . . . . . . . . 6Conservation Step 2: Make a Home for Natural Enemies (Habitat Manipulation) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Augmenting Natural Enemies

Natural Enemies for Hire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11What to Consider When Ordering Natural Enemies. . . . . . . . . . . . . . . . . . . . . . . . . . 11Making Augmentation Successful . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Discovering Natural Enemies in Your Backyard — How to Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Natural Enemies of Common Pests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Predators

Minute Pirate Bugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Stink Bugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Assassin Bugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Damsel Bugs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Bigeyed Bugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Green Lacewings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Ladybugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Rove Beetles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Ground Beetles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Hover Flies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Robber Flies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35Spiders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Parasitoids

Tachinid Flies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37Trichogramma Wasps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40Aphidius Wasps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Table ofContents

Ta b l e o f C o n t e n t s

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Cotesia glomerata. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43Cotesia melanoscelus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44Pteromalus puparum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Diadegma insulare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Tiphia vernalis and T. popilliavora . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46Elm Leaf Beetle Parasitoids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Ooencyrtus kuvanae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Pathogens

Nematodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Beauveria bassiana . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Entomophaga maimaiga . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54Bacillus thuringiensis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55Trichoderma harzianum, Strain T-22 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59Gliocladium virens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

This book summarizes information from the Midwest Biological Control News that is ofinterest to homeowners and gardeners. The newsletter source and contributing authors aregiven at the end of each section. If you are interested in learning more about a particulartopic, you many find the original article and other articles of interest to you in thenewsletter online index at <http://www.entomology.wisc.edu/mbcn/mbcn.html>

We thank the following people for their help and comments: Chris DiFonzo, DeborahMcCullough, Susan Mahr, Dean Krauskopf, Ralph Heiden, Angela Eichorn, Jerry Draheimand Jeanne Himmelein. We also thank Susan Mahr from Midwest Biological Control News,Michael Hoffman, Dave Smitley and Karim Maredia for use of their illustrations andphotos. Many illustrations from Midwest Biological Control News were drawn by Michelle Schwengel.

A c k n o w l e d g e m e n t s

Who are Our Friends in the Garden?Most of us are familiar with spiders,ladybugs and praying mantids and knowthey eat a lot of bad bugs. Luckily, manyother natural enemies are also taking care ofpests. There are three major groups ofnatural enemies: predators, parasitoids andpathogens.

Predators, such asladybugs and spiders,eat many prey in alifetime. Often they arelarger and stronger thantheir prey and the mostvisible natural enemiesin our garden. Some arequick running hunters,while others sit and wait for a victim topounce on.

Parasitoids arespecialized insectsthat develop asyoung in one host,eventually killingit. Unlikepredators, theyusually kill onlyone prey duringtheir immaturestage. Many flies

and wasps are parasitoids, but they areusually small and therefore go unnoticed.

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The home landscape is a complexhabitat possibly consisting ofvegetables, flowers, turf, woody

ornamentals and other desired, and in somecases, undesired plants. For most of us, ourgarden is a relaxing place where we tailor theenvironment to our aesthetic and physicalneeds. Yet the garden is also home tocreatures we consider pests when we findthem in our broccoli or apples or on ourprized rose bushes. As a result, the homelandscape has become the repository ofnearly 11 percent of the conventionalpesticides used in this country. Indeed, acrefor acre, your cousin Vinny's tomato patchhas more pesticides than farmer Joe'ssoybean field! Fortunately, the garden is alsohome to our friends, the natural enemies ofpests.

Most gardeners learn a great deal about theirplants' growth needs, but they often knowlittle about the insects in their gardens. Mostof the insects in a garden are not harmfulpests. The vast majority of insect species inNorth America are either beneficial orharmless to humans and garden plants. To take advantage of the work that naturalenemies do (kill pests), we must first knowwhich ones we have and help them flourish.Using natural enemies to control pestsreduces your need to use pesticides and letsyou take a bite from cousin Vinny's tomatoes,right off the vine!

— MBCN, v.4, n.4, Bryan Schmeiser and BobO'Neil, Purdue University.

C. maculata

Introduction

Wasp on an egg

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Pathogens— nematodes,viruses,bacteria, fungiandprotozoans —cause diseases.Many of thesenaturally occur

in our gardens; others need to beintroduced. Commercial companies havebegun to develop many of these pathogensas bait or spray formulations, making themeasier for us to use.

Making BiologicalControl Work for UsBiological control uses natural enemies tokeep unwanted pests at low levels. To practice biological control in the yard, youshould know the three basic approaches.

Classical biological control is usedwhen pests are exotic in origin and exoticnatural enemies are imported and releasedto bring about control. This is conducted byfederal and state agencies. Although we

homeowners will not be importing naturalenemies into our backyards, some of thenatural enemies described in this book werebrought from other countries andestablished here. The importation of parasiticwasps to control alfalfa weevil in theMidwest has been a widely successfulclassical biological control program.

Conservation biological controlencourages existing natural enemypopulations to flourish in the area andsuppress pests. This involves reducingpractices that harm natural enemies as wellas implementing practices that improvenatural enemy longevity, reproductive rateand effectiveness.

Augmentation biological controlis the release of natural enemies into theenvironment in high numbers. This is donewhen natural enemies do not thrive well inthe environment or are not active during thetime of pest activity. Conservation andaugmentation of natural enemies are thehome gardener's tools to subdue pests, solet's get started!

I n t r o d u c t i o n

nematode

6

Conservation Step 1:Don't Reach for thePesticide SprayTo conserve natural enemies in the homelandscape, first and foremost, we need toreduce insecticide use. The chemicals wespray to get caterpillars off broccoli also killor reduce the livelihood of natural enemies.Natural enemies take longer to re-establishthemselves than pests do. Using pesticidesmay also create new pests because it killsnatural enemies that are suppressing minorpests without our knowledge. When thenatural enemies are killed by a pesticide,these minor pests can become majorproblems.

Kinder Options

Home gardeners have many insect pestmanagement options other than insecticides.Adopting these options with attention to thelife cycles of pest and beneficial insects is akey component of integrated pestmanagement (IPM). Some IPM practicesinclude preplant cultural operations, such asselecting insect-resistant varieties, croprotations and companion plantings. After thegarden has been planted, harmful insectscan be managed in a variety of ways.

• If the garden is relatively small and insectpests are few, hand picking remains one ofthe most effective means of insect controlfor a gardener.

• Traps or barriers can be useful for somepests, and biological control agents thatare commercially available can be veryeffective against specific insect pests. A

word of caution: not all traps are effective(see section on electric traps).

• When all other measures have failed, veryselective and well timed spot treatments ofindividual plant parts with a low-impactinsecticide (such as insecticidal soaps orhorticultural oils, which are relatively safecompounds for beneficials) may beconsidered.

• Tolerating a modest level of insect feedingon your garden vegetables will reduce theneed for chemical inputs. If cabbagewormseat part of your cabbage head, you canalways cut off the nibbled part and use therest.

— MBCN, v.2, n.4, John Obrycki, Iowa StateUniversity, and Susan Mahr, University ofWisconsin - Madison.

Conservation Step 2:Making a Home forNatural Enemies (Habitat Manipulation)Natural enemies require more than just food(pests to eat) to complete their life cycles.Predators and parasitoids may need anoverwintering site, protection from heat anddesiccation, plant food sources and early-season prey to sustain them if pests are notpresent. Managing the garden habitat tomeet the needs of predators and parasitoidsis an excellent way to conserve these gardenfriends and minimize the harmful effects ofcrop production on them.

Overwintering sites — Most pests aregenerally better at dispersal than their naturalenemies, so a garden may get colonized bypests long before natural enemies arrive. For

Conserving Natural Enemies

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Have you or someone you know bought anelectric insect trap to keep the mosquitoesand other biting flies at bay? The snap,crackle and pop of fried arthropods mayseem to confirm their effectiveness, but arethese traps really doing much good? Thetraps in question use ultraviolet light to lurein flying insects, but many species ofmosquitoes are not attracted to light, andmany other non-target insects are attractedto lights and are inadvertently destroyed.

Researchers in Delaware tracked the insectscaught in the electric traps of six homesnear lowland, wooded sites rich in aquaticbreeding habitats and, therefore, close tolots of mosquitoes and no-see-ums. Thesetraps were good at catching insects, theyfound 13,789 insects, but only 31 werebiting flies (a mere 0.22 percent). Nearlyhalf of the insects collected were non-biting aquatic insects such as caddisflies

and midges. More importantly, the trapsdestroyed 1,868 insects from 27 families ofpredators and nine families of parasitoids.Ground beetles, rove beetles and braconidwasps were particularly common victims.Predators and parasitoids accounted for13.5 percent of the trap catch.

By their calculations, the traps needlesslydestroy 71 billion to 350 billion non-targetinsects in the United States each yearwithout achieving any effective control ofnuisance insects. The heavy toll onbeneficial insects suggests that electrifiedtraps may actually be counterproductive forinsect control.

— MBCN, v.3, n.10; T.B. Frick and D.W.Tallamy, 1996, Density and diversity ofnon-target insects killed by suburbanelectric insect traps, Entomology News,107(2): 77-82.

C o n s e r v i n g N a t u r a l E n e m i e s

Electric Traps Get Good Insects But Miss Mosquitoes

may make it harder for flying insects such asaphids and leafhoppers to see the crop byreducing the visual contrast between thefoliage and the soil surface.

Flowers — Having certain flowering plantsavailable can greatly increase the longevityand fertility of many natural enemies. Astudy in Canadian apple orchards showedthat parasitism of orchard pests was four to18 times higher in orchards with manywildflowers than in orchards with fewflowers. A number of plant species havebeen shown to encourage natural enemies(see Table 2). Ladybug and lacewing adultsoften feed on pollen. Many natural enemiesthat benefit from floral nectar are small

this reason, it is all the more important thatoverwintering sites, such as floweringborders, hedges and other perennial habitatsbe provided for natural enemies. Thesevegetative sites insulate natural enemies fromthe winter chill. While some natural enemiesmay overwinter in the bare ground, we laterprepare the ground for planting and disrupttheir homes, sometimes killing them. Whenparts of the garden include undisturbedperennial plantings, natural enemies are morelikely to survive the winter.

Mulches — Using mulches can reduce weedgrowth while providing humid, shelteredhiding places for nocturnal predators such asspiders and ground beetles. Also, the mulch

parasitic wasps, often smaller than amosquito. Consequently, flowers that aregood for them are usually small, not overlytubular and relatively open. In addition,flowers ought to synchronize with naturalenemy activity. Planting a mixture of plantsthat bloom for long periods and overlap intime will ensure that food sources areavailable when natural enemies are active.

Perennial plants often have shorter bloomingperiods than annuals, so particular attentionshould be given to plant diversity andblooming times in perennial bordersdesigned for natural enemies. Sequentialplantings of dill, coriander and caraway canbe made to provide a continuous source ofvaluable flowers.

Ground covers — Leguminous cover cropsimprove soil fertility and provide shelter,floral food sources and alternate prey for awide variety of natural enemies. In covercrops, non-pest prey may be present andsustain natural enemies if their favorite pesthas not invaded the area.

It should be apparent that a single recipe forsuccess using habitat manipulation does notexist. Consider altering gardening practicessuch as planting times, selecting cultivarsand mixing crops together to thwart pestsand enhance natural enemy survival.

— MBCN, v.3, n.4, Shawn Steffan and PaulWhitaker, University of Wisconsin -Madison.

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Garden showing types of habitat manipulation to benefit natural enemies.

Biological control can be used as part of anintegrated pest management program tomaintain the appearance, health andstructural integrity of your valued plantings.The following guidelines will help youmaximize the potential for biological control:

• Monitor your plants regularly to recordplant health, pest and natural enemyabundance, and habitat disturbance.

• Use your records and experience todevelop situation-specific action thresh-olds and particular control strategies.

• When managing pests that occur early inthe season, consider the impacts ofnatural enemies on late-season pests.

• When thresholds are exceeded, usepesticides most compatible with biologicalcontrol. Some chemicals can be usedwithout significantly affecting naturalenemies, but most of the commoninsecticides are broad-spectrum and haverelatively long residual activity. ConsultTable 1 for specific information.

Maximizing Biological Control with Selective Insecticides

Undisturbed Grassy Area

FlowerBorders

FlowerBorders

Mulch AroundPlants

CoverCropsBetweenRows

Class Names Compatibility Comments

Organochlorines Lindane not compatible very long residual, broad-spectrum

Organophosphates Orthene® (acephate) not compatible broad-spectrum

Dursban®, Lorsban® not compatible long residual, broad-spectrum(chlorpyrifos)

Spectracide® (diazinon) not compatible long residual, broad-spectrum

Cygon® (dimethoate) not compatible long residual, broad-spectrum

Carbamates Sevin® (carbaryl) not compatible broad-spectrum; repeated use maystimulate spider mite reproduction

Pyrethroids Ambush®, Pounce® not compatible long residual, broad-spectrum(permethrin)

Botanicals Pyrethrin somewhat compatible short residual but very broad-spectrum

Azatin®, Margosan-O® compatible insect growth regulator derived from (azadirachtin) seeds of neem tree; kills immature

stages; pupal stage parasitoids not affected

Insect growth Dimilin® (diflubenzuron) somewhat compatible moderate residual; kills immature regulators stages pupal stage parasitoids are not

killed

Microbial insecticides Bacillus thuringiensis highly compatible targets caterpillars(pathogen biological var. kurstaki Dipel®,control agents) Thuricide®, Javelin®

(bacteria)

Bacillus thuringiensis highly compatible targets beetle grubsvar. tenebrionis (bacteria)

Beauveria bassiana compatible kills some soft-bodied predators; (fungus) short residual, broad-spectrum

Steinernema carpocapsae highly compatible very low toxicity to humans and non-Biosafe® (nematode) targets, wasp parasitoids with silken

cocoons are not killed

Others Horticultural oil compatible inactive when dry; kills soft-bodied(petroleum oil) insects; pupal stage parasitoids not

killed

Safer®, M-Pede® compatible inactive when dry; kills soft-bodied(insecticidal soap) insects; pupal stage parasitoids not

killed

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Table 1. Pesticide Use Compatibility with Biological Control.

— MBCN, v.6, n.3, Cliff Sadof, Purdue University, and Michael Raupp, University of Maryland.


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Umbelliferae (carrot family)

caraway . . . . . . . . . . . . . . . . . . . . . . . . . . . . Carum carvicoriander (cilantro) . . . . . . . . . . . . . . . . . . . . Coriandrum sativumdill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Anethum graveolensfennel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Foeniculum vulgareflowering ammi or bishop’s flower . . . . . . . . Ammi majusQueen Anne’s lace (wild carrot) . . . . . . . . . . Daucus carotatoothpick ammi . . . . . . . . . . . . . . . . . . . . . . Ammi visnagawild parsnip . . . . . . . . . . . . . . . . . . . . . . . . . Pastinaca sativa

Compositae (aster family)

blanketflower . . . . . . . . . . . . . . . . . . . . . . . Gaillardia spp.coneflower . . . . . . . . . . . . . . . . . . . . . . . . . Echinacea spp.coreopsis . . . . . . . . . . . . . . . . . . . . . . . . . . . Coreopsis spp.cosmos . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cosmos spp.goldenrod . . . . . . . . . . . . . . . . . . . . . . . . . . Solidago spp.sunflower . . . . . . . . . . . . . . . . . . . . . . . . . . Helianthus spp.tansy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tanacetum vulgareyarrow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Achillea spp.

Legumes

alfalfa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Medicago sativabig flower vetch. . . . . . . . . . . . . . . . . . . . . . Vicia spp.fava bean. . . . . . . . . . . . . . . . . . . . . . . . . . . Vicia favahairy vetch . . . . . . . . . . . . . . . . . . . . . . . . . . Vicia villosasweet clover. . . . . . . . . . . . . . . . . . . . . . . . . Melilotus spp.

Brassicaceae (mustard family)

Basket-of-Gold alyssum . . . . . . . . . . . . . . . . Aurinium saxatilishoary alyssum . . . . . . . . . . . . . . . . . . . . . . . Berteroa incanamustards . . . . . . . . . . . . . . . . . . . . . . . . . . . Brassica spp.sweet alyssum . . . . . . . . . . . . . . . . . . . . . . . Lobularia maritimayellow rocket . . . . . . . . . . . . . . . . . . . . . . . . Barbarea vulgariswild mustard . . . . . . . . . . . . . . . . . . . . . . . . Brassica kaber

Other plant families

buckwheat. . . . . . . . . . . . . . . . . . . . . . . . . . Fagopyrum sagittatumcinquefoil. . . . . . . . . . . . . . . . . . . . . . . . . . . Potentilla spp.milkweeds . . . . . . . . . . . . . . . . . . . . . . . . . . Asclepias spp.phacelia . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phacelia spp.


Table 2. Good Flowers for Predators and Parasitoids.

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If naturally occurring predators and parasitesare not sufficient to control garden pests,augmenting them with releases ofcommercially available natural enemies maybe effective. Insect pathogens are oftenproduced as formulations called microbialinsecticides for use in the yard. Not allnatural enemies are available because rearingthem may be difficult or costly.

Natural Enemies for HireWhat is available? Green lacewings arecommonly sold and are a good option foraphid control. These predators can bepurchased and released early in the growingseason for earlier and more effective control.The eggs are shipped in small containersmixed with bran (or another filler, such asvermiculite) that protects the eggs duringshipping. All you have to do is sprinkle thecontents of the container on the plants.Other very popular natural enemies areTrichogramma wasps to controlcabbageworms, cabbage loopers, tomatohornworms and other caterpillars, andbeneficial nematodes to control a widevariety of garden pests. The most commonlyused microbial agent is a bacterium, Bacillusthuringiensis, or Bt. Microbial insecticides aresold by many chemical companies andcommon in stores. If you are interested inpurchasing predators or parasitoids, this is agood free source of information:

— Suppliers of Beneficial Organisms in NorthAmerica by C. D. Hunter, from: CaliforniaEnvironmental Protection AgencyDepartment of Pesticide RegulationEnvironmental Monitoring and PestManagement P.O. Box 942871

Sacramento, CA 94271-0001http://www.cdpr.ca.gov/docs/ipminov/bensuppl.htm

What to Consider When Ordering Natural Enemies

Ask the supplier for specific information andrecommendations for your particularsituation. Ordering and releasing naturalenemies can be successful if you:

• Know the specific pests you need tocontrol.

• Know the best natural enemies, eithersingly or in combination, for the targetpest or pests. Make sure companies

AugmentingNatural

Enemies

12

provide the exact name of the naturalenemy that they are selling.

• Know the proper time to release thenatural enemy. Timing should be basedupon the life cycles of the pest and thenatural enemies.

• Know the proper release rate for eachnatural enemy.

• Calculate the number of natural enemiesneeded on the basis of release rate, area tobe covered and severity of pest infestation.

• Know the recommended frequency ofrelease if multiple releases are necessary.

• Provide a safe delivery address, one wherethe shipment will be cared for as soon asit arrives and where it will not be exposedto temperature extremes.

• Understand proper release practices so thatyou will be prepared to make releaseswhen the shipment arrives.

• Understand proper storage requirements ifreleases are not to be made immediatelyafter arrival.

— MBCN, v.2, n.3.

Ladybugs are good biocontrol agents, butwhat about the ones you buy? Chancesare these ladybugs are Hippodamiaconvergens. Many convergent ladybugsoverwinter in huge aggregations in theSierra Nevada mountains. This makes iteasy for suppliers to scoop them up, boxthem and sell them. Unfortunately, whenyou release these convergent ladybugs inyour backyard, they behave as they do inthe mountains — they fly away lookingfor the valley, their normal feedinggrounds. Some suppliers are nowpreconditioning ladybugs, letting them flyaround before you receive them so theladybugs will be less likely to fly away. Ifyou're interested in testing ladybugs inyour backyard, look for the activity box inthe ladybug section.

What about praying mantids? Thoughthey certainly do prey on pests, mantidsare extreme generalists — they will eatvirtually anything they can catch, includingtheir siblings and other beneficials. Largemantids, such as the commerciallyavailable Chinese mantid, will even catchand eat bees and other pollinators. Adultmantids are very mobile, so they usuallywon't remain in the release site for long.Nevertheless, they are interesting. Becauseof their large size, big and seeminglyinquisitive eyes, and their “praying”stance, we seem to have an affinity forthem. If you wish to purchase them, do soas a source of education or interest, butdon't expect them to provide muchbenefit in pest management.

- MBCN, v.2, n.4, Dan Mahr, University ofWisconsin - Madison.

Making AugmentationSuccessful

Releasing loads of natural enemies in thegarden will take money from your pocket,but will it guarantee success? Sometimespredators and parasitoids will leave the areaor will not survive long enough to have animpact on pests. Maintaining a suitablehabitat, as discussed in conservationbiological control, is critical to improving thenatural enemy's efficacy. Be very judicious

What About Releasing Ladybugsand Praying Mantids?

A u g m e n t i n g N a t u r a l E n e m i e s

13

We often look to biological control to worklike chemical controls. It would be nice ifone natural enemy was the silver bullet andtook care of the pest. Yet natural enemiesoften do not work that way. Releasing afantastic predator and having it becomeestablished in the system requires effort.We need to know what the predator needsand make sure alternative food sources andprotective shelter are provided. As you lookthrough this book, you will notice thatsome natural enemies eat a variety of pestsand others are very specific. Both areusually needed to obtain effective biologicalcontrol. Some specific natural enemies can

be very good at locating pests at lowdensities and keeping them low, whileother specifics may be good at bringingdown pest outbreaks. Generalists areimportant because they can feast on avariety of pests and are more flexible inwhere they can live. When a particularlybad pest arrives, the generalist naturalenemies are already in your garden ready todo their share of eating away the pestpopulation. Biological control of pests maytake many natural enemies and more efforton your part, but it can work in yourgarden!

A u g m e n t i n g N a t u r a l E n e m i e s

with insecticide use when releasing naturalenemies. Commercially reared insects willlikely find it just as hard to survive insecticideexposure as your normal yard insects. Also, adiversity of plantings (flowering plants,ground covers) will help maintain anadequate food supply and shelter so releasednatural enemies will remain in your gardendoing what you paid for them to do.

Looking for the Silver Bullet

14

Your garden contains a wealth of smallcritters. We tend to notice the bad orpretty ones, but there are plenty more

out there — we just need to keep an eyeopen for them. Here is how you can discoverthe wonderful diversity of insects and othercritters.

• Spend an hour or two outside sittingquietly and observing. When flowers are inbloom, there is a lot of activity — manyflower feeders and pollinators come by. Ifyou are lucky, you might see a predatorthat was hiding in the flower leap out andattack its unsuspecting prey. If the planthas aphids, you may notice a ladybug orother predator feeding on them.Sometimes you may see ants taking care ofthe aphids. The aphids provide ants withhoneydew, so the ants will guard themagainst any predator.

• Dig up some soil and spread it out on awhite surface. You'll probably seeearthworms, a good sign. Perhaps thereare little things jumping about. Thesespringtails are important decomposers andrelatively harmless to crops. You may alsosee less mobile pupae and grubs as well asadult ground beetles that run franticallywhen disturbed.

• Put bright yellow cards covered inpetroleum jelly in various areas — in treefoliage, above grasses and in yourvegetable planting. Why bright yellow?This color is attractive to many pest and

beneficial insects. The traps will kill them,so it is advisable not to keep them out forlong. Adult parasitoids, small wasps, oftenfly into these traps, and you never knewthey were there before in your garden.

• Fill yellow plastic pans with soapy waterand place them on the ground. Manyaphids and flies will find their way into thepans.

• Make pitfall traps by inserting plastic cupsinto the soil with the rim just below the soilsurface so that any strolling insects will fallin. Leave them out overnight and you maybe surprised by the number of grounddwellers active at night. Spiders andground beetles, both good predators, willdominate the traps. If there are insectremains, they may have been feasting onone another through the night.

• Place a white sheet under a tree or bush.Beat the branches with a stick or shakethem with your hands. You will find thatspiders, true bugs, caterpillars and sawfliescome tumbling down.

Discovering Natural Enemies in Your Backyard — How to Sample

Aphids

Beetles

15

Minute pirate bugs (predator) ..........................................21Assassin bugs (predator) ..................................................24Damsel bugs (predator)....................................................24Bigeyed bugs (predator)...................................................25Green lacewings (predator)..............................................26Ladybugs (predator).........................................................27Ground beetles (predator)................................................32Hover flies (predator) .......................................................34Aphidius wasps (parasitoid) .............................................42Beauveria bassiana (pathogen).........................................52

Natural Enemiesof Common

Pests

Minute pirate bugs (predator) . . . . . . . . . . . . . . . . . . . . . 21Assassin bugs (predator) . . . . . . . . . . . . . . . . . . . . . . . . . 24Damsel bugs (predator). . . . . . . . . . . . . . . . . . . . . . . . . . 24Bigeyed bugs (predator) . . . . . . . . . . . . . . . . . . . . . . . . . 25Green lacewings (predator). . . . . . . . . . . . . . . . . . . . . . . 26Ladybugs (predator) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Ground beetles (predator). . . . . . . . . . . . . . . . . . . . . . . . 32Hover flies (predator) . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Beauveria bassiana (pathogen) . . . . . . . . . . . . . . . . . . . . 52

Natural Enemies of Beetles Page

Natural Enemies of Aphids Page

With this table, you can quickly identify the particular natural enemies that can help controlcommon pests in your garden and home landscape. Look in the left column for the pest youwant to control. The right column will guide you to the pages for more information.

Caterpillars

Beetles

Bugs

16

N a t u r a l E n e m i e s o f C o m m o n P e s t s

Colorado potato beetle Spined soldier bug (predator) . . . . . . . . . . . . . . . . . . . . . 22Two-spotted stink bug (predator) . . . . . . . . . . . . . . . . . . 23Tachinid fly, Myiopharus doryphorae (parasitoid) . . . . . . . 38

Elm leaf beetle Tetrastichus gallerucae and Tetrastichus brevistigma (parasitoids). . . . . . . . . . . . . . . . 47

Japanese beetle Tachinid fly, Istocheta aldrichi (parasitoid) . . . . . . . . . . . . 39Tiphia vernalis and Tiphia popilliavora (parasitoids) . . . . . 46Nematodes (pathogen) . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Other grubs Robber flies (predator) . . . . . . . . . . . . . . . . . . . . . . . . . . 35Nematodes (pathogen) . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Natural Enemies of Beetles Page

Natural Enemies of Bugs Page

Natural Enemies of Caterpillars Page

Specific Beetle Pests

Damsel bugs (predator). . . . . . . . . . . . . . . . . . . . . . . . . . 24

Bigeyed bugs (predator) . . . . . . . . . . . . . . . . . . . . . . . . . 25

Tachinid flies, feather legged fly (parasitoids). . . . . . . . . . 38

Beauveria bassiana (pathogen) . . . . . . . . . . . . . . . . . . . . 52

Minute pirate bugs (predator) . . . . . . . . . . . . . . . . . . . . . 21Spined soldier bug (predator) . . . . . . . . . . . . . . . . . . . . . 22Assassin bugs (predator) . . . . . . . . . . . . . . . . . . . . . . . . . 24Damsel bugs (predator). . . . . . . . . . . . . . . . . . . . . . . . . . 24Bigeyed bugs (predator) . . . . . . . . . . . . . . . . . . . . . . . . . 25Green lacewings (predator). . . . . . . . . . . . . . . . . . . . . . . 26Ground beetles (predator). . . . . . . . . . . . . . . . . . . . . . . . 32Hover flies (predator) . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Tachinid flies (parasitoid) . . . . . . . . . . . . . . . . . . . . . . . . . 37Trichogramma wasps (parasitoid) . . . . . . . . . . . . . . . . . . 40Beauveria bassiana (pathogen) . . . . . . . . . . . . . . . . . . . . 52Bacillus thuringiensis var. kurstaki (pathogen) . . . . . . . . . 55

Grasshoppers

17


Caterpillars

Flies

Cabbage looper Tachinid fly, Voria ruralis (parasitoid). . . . . . . . . . . . . . . . 37

Diamondback moth Diadegma insulare (parasitoid). . . . . . . . . . . . . . . . . . . . 45

Gypsy moth Ground beetle, Calosoma sycophanta (predator) . . . . . . 33Tachinid fly, Compsilura concinnata (parasitoid) . . . . . . . 38Cotesia melanoscelus (parasitoid). . . . . . . . . . . . . . . . . . 44Ooencyrtus kuvanae (parasitoid) . . . . . . . . . . . . . . . . . . 48Entomophaga maimaiga (pathogen) . . . . . . . . . . . . . . . 54

Imported cabbageworm Cotesia glomerata (parasitoid) . . . . . . . . . . . . . . . . . . . . 43Pteromalus puparum (parasitoid) . . . . . . . . . . . . . . . . . . 45

Natural Enemies of Caterpillars Page

Natural Enemies of Flies Page

Natural Enemies of Grasshoppers Page

Specific Caterpillar Pests

Rove beetles (predator) . . . . . . . . . . . . . . . . . . . . . . . . . 31

Ground beetles (predator) . . . . . . . . . . . . . . . . . . . . . . . 32

Robber flies (predator) . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Tachinid flies (parasitoid) . . . . . . . . . . . . . . . . . . . . . . . . 37

Beauveria bassiana (pathogen). . . . . . . . . . . . . . . . . . . . 52

Specific Fly Pests

Cabbage maggot Rove beetle, Aleochara bilineata (predator) . . . . . . . . . . 31

Mosquitoes Bacillus thuringiensis var. israelensis (pathogen) . . . . . . . 55

Sawflies

Mites

18


Mealybugs

Assassin bugs (predator) . . . . . . . . . . . . . . . . . . . . . . . . 24

Damsel bugs (predator) . . . . . . . . . . . . . . . . . . . . . . . . . 24

Bigeyed bugs (predator). . . . . . . . . . . . . . . . . . . . . . . . . 25

Natural Enemies of Leafhoppers Page

Natural Enemies of Mealybugs Page

Natural Enemies of Mites Page

Natural Enemies of Sawflies Page


Green lacewings (predator) . . . . . . . . . . . . . . . . . . . . . . 26

Ladybugs (predator). . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Minute pirate bugs (predator) . . . . . . . . . . . . . . . . . . . . 21






Tachinid flies (parasitoid) . . . . . . . . . . . . . . . . . . . . . . . . 37

Leafhoppers

Whiteflies

Thrips

19


Plant pathogens Natural Enemies of Plant Pathogens Page

Trichoderma harzianum, strain T-22 (pathogen) . . . . . . . 59

Gliocladium virens (pathogen) . . . . . . . . . . . . . . . . . . . . 60

Root rot by Fusarium,Pythium and Rhizoctonia

spp. fungi

Scales

Snails, Slugs




Natural Enemies of Scales Page

Natural Enemies of Snails, Slugs Page

Natural Enemies of Thrips Page

Natural Enemies of Whiteflies Page


Ground beetles (predator) . . . . . . . . . . . . . . . . . . . . . . . 32



Hover flies (predator) . . . . . . . . . . . . . . . . . . . . . . . . . . . 34




20

Predators kill more than one prey in theirlifetime. Birds, mice, frogs, insects andother arthropods all eat insect pests.

For pest management, the six-legged andeight-legged creatures, insects andarachnids, are the most important controlagents.

Predators may be stronger and larger thantheir victims. Some ground-dwellingpredators have long running legs and use

speed to catch prey. Others are camouflagedand strike when prey are in close range.Some really smart predators build traps tobring them dinner. Have you seen cone-shaped pits in sandy ground? At the bottomof the pit is a young ant lion waiting for anant to stroll by. When an ant walks near, theyoung ant lion throws up sand to get the antto tumble down into the pit. Using strength,speed or trickery, predators can catch and eata lot of prey, and that is good news for us.

Predators

Insects develop in two major ways, and the type of development will influence the naturalenemy's lifestyle and how you recognize it. While, all adult insects have six legs, twoantennae and a three-part body plan: head, thorax and abdomen, immature insects may lookdifferent depending on their type of development.

Hemimetabolous insects:the young insects look like theadult insects without wings.

Both nymph and adult tend toeat the same things. Predaceoustrue bugs are hemimetabolous.Arachnids, including spiders andmites, develop similarly tohemimetabolous insects.

Holometabolous insects: the young insect looks drastically different from the adult.

The larva and adult mayfeed on different foods andlive in different habitats.Beetles, lacewings, waspsand flies are holometa-bolous. Beetle larvae areoften called grubs, and flylarvae are called maggots.

Development

Egg Nymph Adult

Egg Larva Pupa Adult

21

All true bugs (orderHemiptera) havepiercing-suckingmouthparts. Thesemouthparts extend intoa long “beak” known asa rostrum. Most truebugs are plant feeders,but many arepredaceous, drinking theblood of other insects,and a rare few canattack humans. Truebugs have their own tricks of the trade forcatching insects. The stink bugs and smallflower bugs often attack less mobile victimssuch as caterpillars, slow larvae and aphids.Assassin bugs may lie hidden and jumpwhen a good-looking dinner crosses theirpath. Some bugs emit attractive odors tolure bees in. Once a victim is seized, the

sharp teeth at the tip ofthe bug's rostrum busilycut a hole. The bug thensticks its rostrum insidethe prey, pumpsenzyme-laden saliva andsucks up the partiallydigested insect cocktailthrough its ownpersonal straw.

Should we be wary ofthese blood suckers?

Well, the human blood suckers, such asbedbugs, are relatively uncommon. Theones we find in our yard prefer to feed onother insects, though they can poke you ifyou bother them. Large bugs can deliverpainful bites that may cause blistering, sobe careful if you handle them.

lay tiny eggs withinplant tissues wherethey are not easilyseen or eaten byother predators.These eggs hatchinto immaturenymphs. Nymphs aresmall, winglessinsects, yellow-orange to brown,teardrop-shaped andfast moving. Growing from egg to adulttakes at least 20 days under optimumconditions. Several generations may occurduring a growing season.

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True Bugs, Blood Suckers of the Insect World

Minute Pirate BugsOrder: Hemiptera, true bugsFamily: Anthocoridae

Pirate bugs are common insect predatorsfound in many habitats, includingagricultural crops, pastures and homelandscapes. Both immature stages (nymphs)and adults feed on a variety of small prey,including spider mites, insect eggs,aphids, thrips, scales and smallcaterpillars.

What you will see: Adults are very small— 1/8 inch long — somewhat oval-shapedand black with white wing patches. Females

Minute Pirate Bug

22

Orius spp. The most common species inthe Midwest is Orius insidiosus. Anotherspecies, Orius tristicolor, is more common inwestern states. Both immature and adultOrius can consume 30 or more spider mitesper day. They also eat potato aphids andpotato leafhopper nymphs. Occasionally,Orius may even bite humans, but the bite isonly temporarily irritating.

Giving them a boost: Grow a variety ofspring- and summer-flowering shrubs andplants — pirate bugs will feed on pollen andplant juices when prey are not available.Insecticides can greatly reduce their num-bers. Even soil-applied systemic insecticidesmay reduce their numbers because they mayingest them by sucking plant juices formoisture. Diversified cropping systems or useof selective products such as microbialinsecticides will maximize the naturalbiological control from minute pirate bugs.

If you would like to give your garden anextra boost of minute pirate bug activity, youcan buy Orius from commercial suppliers.These bugs are shipped as adults in a carriersuch as vermiculite along with a food source.Shake the carrier onto your plants and thebugs will readily disperse and locate prey.

— MBCN, v.1, n.1, Bob Wright, University ofNebraska - Lincoln.

Stink BugsOrder: Hemiptera, true bugsFamily: Pentatomidae

If you have picked up a stink bug, you mayrecall the unpleasant smell of your handafterwards. Stink bugs are quite distinguish-able by their broad, shield-shaped bodies.

Many stinkbugs are plant feeders, but someare important predators. The spined soldierbug and the two-spotted stink bug feed on avariety of pests and are particularly famousbecause they feed on Colorado potatobeetle.

Spined soldier bug (Podisusmaculiventris) — This stink bug can feedon more than 50 types of prey, primarily thelarvae of beetles and moths. The largest,most sustained attempt at releasing spinedsoldier bugs in a biological control programagainst Colorado potato beetle occurred ineastern Europe and the former Soviet Union(see MBCN, v.4, n.1). Millions of spinedsoldier bugs were reared and released, withvery promising results.

What you will see: Adult spined soldierbugs are brownish and about 1/4 inch longwith a prominent spine on each “shoulder.”(This is not the origin of the name spinedsoldier bug . . . “spined” refers to spines onthe legs.) They overwinter as adults, hiding inleaf litter in woods around fields, and beginemerging around mid-April. Females can layup to 500 eggs and live up to 125 days.Males are slightly smaller than females andlive up to 180 days.

Females begin depositing eggs four to sevendays after emerging. The number of eggs afemale lays depends on how well she is fedand what she fed on. The eggs are depositedin masses of 15 to 70 and range from cream-colored to black. Eggs hatch in four to sevendays, depending on temperature. The brick-red first instar spined soldier bugs are notpredaceous (they eat nothing at all); theremaining four instars (nymphal stages) arepredaceous. Development from newlyhatched nymph to adult takes 25 to 30 days.There are one to three generations per year.

P r e d a t o r s

23

Two-spotted stink bug (Perillusbioculatus) —These bugs eat caterpillarsas well as Colorado potato beetle eggsand larvae. Two-spotted stink bugs feedmore specifically on Colorado potato beetleand prefer smaller larvae than the spinedsoldier bug.

What you will see: Two-spotted stinkbug adults are black with yellow or redmarkings. A distinctive black Y appears ontheir back or shield. Adults emerge in earlyspring and feed on plant sap before prey areavailable. The life cycle is similar to that ofthe spined soldier bug. The first instar feedson plant sap; later instars are predaceous.

Giving them a boost: Having year-roundground cover present in your garden willprovide them an overwintering home andplant sap for supplemental food when preyare scarce. Commercial suppliers have spinedsoldier bugs and two-spotted stink bugs onhand. If nymphs are purchased, be awarethat they are delicate and need to bereleased soon, and that transporting them

onto potato foliage is time consuming. Eggsare easier to handle but should be placed inprotective screened containers on the soil toprevent them from being eaten by others.

— MBCN, v.2, n.8; v.3, n.5, Bob O'Neil,Purdue University; J. Hough-Goldstein, J. A. Janis and C.D. Ellers, 1996, Releasemethods for Perillus bioculatus (F.), apredator of the Colorado potato beetle,Biological Control, 6: 114-122.

P r e d a t o r s

egg mass nymph adult

Spined soldier bug

Two-spotted stink bug

24

Assassin BugsOrder: Hemiptera, true bugsFamily: Reduviidae

The more than 160 species in the familyReduviidae in North America include assassinbugs, ambush bugs and thread-legged bugs.Most assassin bugs are medium to largepredators of crop pests, but the family doescontain a few blood-sucking species. Thesebeneficial insect predators can inflict apainful bite if handled carelessly, resulting inan inflammation that can persist for a fewdays. Most assassin bugs are generalistpredators in gardens, fields and forests.

narrow with a distinct “neck” behind theoften reddish eyes. The long beak or rostrumis carried beneath the body, with the tipfitting in a groove on the underside of thebody. The middle of the abdomen is oftenwidened, so the wings don't completelycover the width of the body. The female layseggs in tight, upright clusters on leaves or inthe soil. Nymphs resemble miniature,wingless adults.

Wheel bug (Arilus cristatus) — This isone of the largest and most easilyrecognized assassin bugs. The adult is about1 1/4 inches long and gray with a strikingsemicircular crest on the upper back thatlooks like a cogwheel. Wheel bugs feed onaphids as young nymphs. Later they attackcaterpillars such as the fall webworm andother pests such as the locust borer.

Giving them a boost: Assassin bugs arenot often manipulated for pest control, butjudicious use of insecticides can help increasetheir activity.

— MBCN, v.3, n.5, Susan Mahr, University ofWisconsin - Madison.

Damsel BugsOrder: Hemiptera, true bugsFamily: Nabidae

These generalist predators are commonlyfound in many crop and garden situations.They are predators of aphids, moth eggsand small caterpillars, including importedcabbageworm and some armyworms.Other prey may include leafhoppers(including beet and potato leafhoppers),small sawfly larvae, mites, tarnishedplant bug nymphs, and asparagus beetle

P r e d a t o r s

Assassin bug

They sit in wait for prey and are most likelyto attack small flying insects, though theycan subdue and kill medium-sizedcaterpillars. Prey in vegetable plantings caninclude aphids, leafhoppers andasparagus beetle eggs and larvae.Assassin bugs may feed on beneficial speciesas well as pests.

What you will see: Adult assassin bugsare usually 1/2 to 3/4 inch long. Manyspecies are brownish or blackish, but someare brightly colored. The elongated head is

25

and Colorado potato beetle eggs andlarvae. Though they can survive for up totwo weeks without food, they becomecannibals if no other prey is available.

What you will see: Damsel bugs areslender, tan-colored bugs that resemblesmall, smooth-looking assassin or other plantbugs that feed on crops. Some damsel bugspecies are black. Most species of damselbugs overwinter as adults and can have oneto five generations per year, depending onlocation.

Giving them a boost: Maintain low-growing grasses or ground cover in yourgarden; damsel bugs prefer to take shelter inthese environments. Damsel bugs arecurrently not available from commercialsuppliers.


Bigeyed BugsOrder: Hemiptera, true bugsFamily: Lygaeidae, seed bugsGenus: Geocoris spp.

Bigeyed bugs, Geocoris spp., are generalistpredators commonly found in a variety ofcrops, home gardens and lawns. Manybigeyed bug species are found throughoutthe United States feeding on insect eggs,aphids, mealybugs, spider mites,leafhoppers, plant bugs, whiteflies, andsmall caterpillars or beetle larvae. Eachnymph may consume up to 1,600 spidermites during its immature stages and asmany as 80 mites a day as an adult. Bigeyedbugs are fun to watch — they attack prey byextending their beak and quickly inserting itinto the prey. These small bugs may lift preyinto the air to prevent it from escaping.

What you will see: As the name implies,bigeyed bugs have rather large, protrudingeyes. The adults range in color from blackand white to tan. The nymphs resemble

P r e d a t o r s

Damsel bug

Bigeyed bug

26

miniature grayish adults. They are small,about 1/8 to 3/16 inch long. Most bigeyedbugs go through five nymphal stages. Underlaboratory conditions, nymphs develop intoadults within 30 days at 77 degrees F and 60 days at 68 degrees F. Bigeyed bugsoverwinter as adults or as eggs, dependingon the species and location.

Giving them a boost: Bigeyed bugsprefer weedy areas of gardens. They feed onplants and survive best when they have a mixof plant and insect food. Be aware that theirplant-feeding habit makes them alsosusceptible to systemic insecticides. Thegood news is that their omnivorous feedinghabits allow them to survive in a variety ofhabitats, and there is no evidence that theirplant feeding causes significant injury toplants.

— MBCN, v.4, n.12, Bob Wright, Universityof Nebraska.

Green LacewingsOrder: NeuropteraFamily: Chrysopidae

Green lacewings are found in mostenvironments throughout North America.The larvae of green lacewings, calledaphidlions, are voracious predators in manybiocontrol programs. Aphidlions canconsume up to 200 aphids per week. Theyalso eat mites, insect eggs, thrips, mealy-bugs, immature whiteflies, scales andsmall caterpillars. Adult green lacewingsare generally not predaceous, consumingplant nectar, pollen and honeydew.

P r e d a t o r s

Lacewing larva

Lacewing adult

What you will see: The light greenlacewing adult has long, slender antennae,golden eyes, and large, veined, gauzelikewings that are 1/2 to 1/3 inch long. It is aslow-flying nocturnal insect that feeds onnectar and pollen. It emits a foul-smellingfluid from special glands if captured. Thefemale lacewing lays eggs in groups onleaves, each egg held away from the leafsurface on the end of a slender stalk. A female can lay 300 eggs over a period ofthree to four weeks, but the eggs often donot survive that long in the field. Theaphidlion larva resembles a green-grayalligator with mouthparts like ice tongs. Anaphidlion seizes and punctures its prey withlong, sickle-shaped jaws, injects a paralyzingfluid and sucks out the body fluids. After

27

feeding and growing to 1/2 inch in lengthduring a two- to three-week period, thelarva spins a spherical, white silken cocoonto pupate. The adult emerges in about fivedays. It overwinters as a pupa within itscocoon or as an adult.

Giving them a boost: Have floweringplants blooming throughout the season —adult lacewings need nectar and pollen tofeed on and stimulate egg laying. Greenlacewings are widely available from manycommercial suppliers, generally offered aseggs. Aphidlions will travel 80 to100 feet insearch of prey. For control of moderate aphidinfestations in home gardens, release five to10 lacewing eggs per plant or 1,000 eggsper 200 square feet. Two or three successivereleases made at two-week intervals arebetter than a single release. These insects areextremely effective under certain conditions,especially in protected or enclosed areas suchas a greenhouse, but they may fail to survive

and provide control when conditions are notfavorable. Providing a suitable habitat foradults will encourage released lacewings toremain in your garden. Otherwise, you willneed to make additional releases to maintaina continuous supply of larvae.


Ladybug, Ladybird, Lady BeetleOrder: Coleoptera, beetlesFamily: Coccinellidae

Ladybugs have been appreciated forcenturies. During the Middle Ages, farmersprayed to the Virgin Mary when aphids wereattacking their crops. When these beetlesarrived and consumed the aphid problem,they were called “Our Lady”, hence the

P r e d a t o r s

Ever noticed insect eggs on a slender stalk? Why would a mother lay her eggs that way? It isnot to let the wind gently blow on them but to prevent them from being eaten. Thepredaceous green lacewings are mighty good predators, and once hatched, they are sodetermined to eat that they would eat their own siblings. The mother lays her eggs on a stalkto keep them out of reach of hungry brothers and sisters.

Sibling Rivalry

Purchase a praying mantid egg case or find one in your backyard. Place the egg case in a jar.Put lots of very small insects and their plant food inside. Wait for eggs to hatch. Watch theyoung brother and sister mantids hunt the small insects. About how many mantids hatched?How many mantids are left after a week? Where did the rest go? Place the remaining mantidsin the garden.

Fun for Kids

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name “ladybug”. The family of ladybugscontains more than 4,000 species. Nearly allare predators, and they feed on many kindsof soft-bodied insects: aphids, mealybugs,whiteflies and scales. As early as the late1800s, lady beetles were being used inbiological control programs in the UnitedStates. The importation of the predaceousvedalia beetle, a scale-feeding species, savedthe citrus industry in California from thecottony cushion scale.

What you will see: Many of us arefamiliar with adult ladybugs. They are shiny,convex, round, sometimes red-orange orblack, and with and without spots. Larvaeare less well known but also very importantpredators. The size and coloration of thelarval stages vary among species, butgenerally larvae are soft-bodied and shapedlike miniature alligators. Newly hatchedlarvae are gray or black and less than 1/8inch long. Later stage larvae can be gray,black or blue with bright yellow or orangemarkings.

Twelve-spotted lady beetle(Coleomegilla maculata) — Adults areabout 1/4 inch long and have pink to lightred wing covers with six black spots on eachwing. Both adults and larvae feed onaphids, mites, insect eggs and smalllarvae of many insect pests. Plant pollen andfungal spores are also important componentsof their diet. Females lay clusters of 10 to 20yellow eggs on plants. This species has twoto three generations per year in the Midwestand overwinters as large groups of adults inthe litter at the bases of trees or next tobuildings.

Convergent lady beetle (Hippodamia convergens) — Adults areabout 1/4 inch long with orange wingcovers, typically with six small black spots oneach wing cover or sometimes with no spots.

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Ladybug larva

In the Midwest, several very common ladybeetle species are aphid predators.

C. maculata

Convergent lady beetle

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The section of the body behind the head isblack with white margins and has twoconverging white lines; this is why it is calledthe convergent lady beetle. Adults and larvaefeed primarily on aphids. Females layclusters of 10 to 20 yellow eggs on plantsinfested with aphids. The larvae grow andmolt through four stages. This speciesprobably has one to two generations eachyear in the Midwest. Large aggregations ofconvergent lady beetles in the Sierra Nevadamountains of California are collected forcommercial sale.

Two-spotted lady beetle (Adaliabipunctata) — As one might expect fromits common name, these red beetles havetwo black spots. The 1/4-inch-long adults arecommonly found in trees and bushes. Theyoverwinter in or around buildings or in otherprotected locations and emerge in early tomidspring.

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Seven-spotted lady beetle

Two-spotted lady beetle

Multicolored Asian lady beetle

Seven-spotted lady beetle(Coccinella septempunctata) — The seven-spotted lady beetle wasintroduced into North America from Europe.Adults are large — about 3/8 inch — withred wing covers with seven black spots.Females lay clusters of 15 to 70 yellow eggson plants that are infested with their aphidprey. Larvae grow and molt through fourstages as they feed on aphids. The largefourth instar consumes more aphids than theprevious three larval stages combined. Adultseven-spotted lady beetles overwinter insmall groups in hedges or in leaf litter on theground near the bases of plants.

Multicolored Asian lady beetle(Harmonia axyridis) — Adults are yellowto orange and often seen in largecongregations on buildings around the endof October. This lady beetle was introducedfrom Japan to control tree-inhabiting aphids.It feeds on various aphids, certain scalesand a few other insects. It is an effectivepredator of aphids on pecans, pine trees,ornamental shrubs, roses and other plants. Inthe South, many pecan growers no longerneed to spray their trees for pecan aphids

Ladybugs are often offered for sale forcontrolling aphids in home gardens. Asmentioned, releases have not often beensuccessful. Nevertheless, you may be curiousabout buying ladybugs and testing them.

• Select several plants (or branches of atree) that have aphids on them for yourtest plants. Mark eight to 12 brancheswith tags so you can easily locate them.Count or estimate the number of aphidson each branch, and record thisinformation.

• Enclose half of the branches in cages andleave the rest exposed. You can makesimple cages with mosquito netting orother mesh fabric. Cut out a square pieceof netting and fold it in half. Sew thelong side and the bottom shut. Or, if thebranches are small, try pantyhose. Insertyour aphid-infested branch into this"sleeve cage" and tie it closed with apiece of string. Do remove any natural

enemies that might be on the branchesbefore putting on the cages.

• Release about five ladybugs on half of theexposed branches and half into thecages. The remaining exposed and cagedbranches will be your controls. You nowhave four treatments: exposed branchwith ladybugs, exposed branch withoutladybugs, caged branch with ladybugsand caged branch without ladybugs.

• Inspect the branches for ladybugs andcount the number of aphids on thebranches again in three days, a week andtwo weeks.

Now that you have run your backyardscience experiment, what happened? Howhave the aphid populations changed? Wereany ladybugs still on the exposed branches?If not, where do you suppose they went?Do you think the exposed aphids wereeaten by the ladybugs you released or werethey destroyed by other naturally occurring

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because this lady beetle has done such agood job of biological control.

The adult multicolored Asian lady beetle isquite variable in appearance. Individuals canbe any color from a pale yellow-orange to adeep orange-red with no spots or up to 20black spots. They are very prolific and maylive up to three years. The bright yellow eggsare laid in clusters of about 20 on theundersides of leaves. The eggs hatch in threeto five days, and the larvae feed up in thetrees for 12 to 14 days. They then pupate onthe leaves. Adults emerge in five to six days.

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Giving them a boost: Reduce insecticideuse or pick selective insecticides. Plant avariety of crops so that ladybugs have avariety of prey available throughout theseason. Adults need nectar and pollen, somake sure flowering plants are around.Though ladybugs are available for sale,augmentative releases have not been highlysuccessful.

— MBCN, v.2, n.4, John Obrycki, Iowa StateUniversity; MBCN, v.2, n.10, Susan Mahr,University of Wisconsin - Madison.

The Scientist in You:

How Do Ladybug Releases Affect Aphids in Your Garden?

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Have you noticed that, when the weathergrows cold, you start finding ladybugs onyour table, on the windowsill or in yourcup? Even though the multicolored Asianlady beetle is an important biologicalcontrol agent, it can become a nuisancewhen large numbers aggregate in homesor other buildings. For several days duringautumn, they typically hang out on sunny,southwest sides of light-colored rockoutcroppings or structures where nearbycrevices serve as overwintering sites.Outdoor clusters may leave after a fewdays or weeks.

The best way to prevent beetles frombecoming uninvited houseguests is to sealcracks around windows, doors, siding,utility pipes or other openings with a goodquality caulk. Replace or repair damagedscreens, and install screens over roof vents.Indoor visitors can be removed with avacuum cleaner equipped with a crevicetool. They can also be swept up with abroom and dustpan and be depositedoutside well away from the house. It is nota good idea to kill them with insecticides,squash them or handle them, as this mayresult in orange stains on walls and fabric.When stressed, the lady beetles secrete aharmless but staining orange substance.

— MBCN, v.2, n.10, Susan Mahr,University of Wisconsin - Madison.

Collect some ladybugs. Hold them andpoke them gently. Notice how they pulltheir legs into their bodies and an orangeliquid comes out. This liquid is blood thatcomes out of the joints of the legs in aphenomenon called reflex bleeding. Alllady beetles do this when threatened.Their blood is distasteful to birds andother prospective predators. Afterwards,free the ladybug so it can relax again.

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Ladybugs: Friends in the Home? Fun for Kids: How LadybugsDefend Themselves

biological control agents? Did caging theladybugs to keep them from flying awayimprove aphid control? Do you think it is

worth the cost to buy ladybugs to releasein your garden?

– MBCN, v.2, n.6, Susan Mahr, University ofWisconsin - Madison.

Rove BeetlesOrder: Coleoptera, beetlesFamily: Staphylinidae

There are about 2,900 species of rovebeetles in North America. Some species arepredaceous as both adults and larvae; thelarvae of other species are parasitoids; manyothers are probably scavengers. They areoften found in agricultural soils and homegardens. Predaceous rove beetles mayconsume root maggot eggs and larvae,mites, small insects, snails and insect eggs onthe ground or sometimes on foliage.

What you will see: Adult rove beetles aregenerally less than 3/4 inch long. They areeasily recognized by their slender, usuallyblack or brown body and shortened front

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wings (elytra) that may look like pads on theabdomen. They may curl the tip of theabdomen upwards when disturbed orrunning, like a scorpion. Adults are usuallystrong fliers. The mobile larvae of non-parasitic rove beetles may be distinctlysegmented. Rove beetles may be seen underdebris or rocks, in compost piles or onplants.

Aleochara bilineata rove beetles have adual lifestyle — as larvae, they are parasiticon cabbage maggot pupae, and as adultsthey become hunting predators of cabbagemaggots. The 1/8-inch-long adults areglossy black except for the short wingcovers, which are a reddish brown. Adultsemerge in spring and deposit eggs in the soilnear the roots of maggot-infested plants.When larvae hatch within five to 10 days,they search for host puparia in thesurrounding soil. They gnaw holes in thepuparia, enter and feed on the maggotpupae for about three weeks. After theirlong meal, these rove beetles pupate withinthe host puparia, and adults emerge after amonth or more. Aleochara adults thendestroy eggs or young maggots near the soil

surface and maggots in the plant roots. Theymay consume up to five root maggot larvaeand 23 eggs per day.

Giving them a boost: Make sure an areaof your garden has grassy cover during thewinter — rove beetles hibernate in thesesites in great numbers. Be selective withchemicals — they are very sensitive toinsecticide exposure. In some cases, as withAleochara bilineata, the beetles do not oftenemerge early enough in the spring toprevent early-season root damage.Augmentative releases may provide early-season maggot control. As of now, A. bilineata is not commercially available inNorth America, but it has been mass rearedin Europe and Canada, and in time they maybe commercially available.


Ground BeetlesOrder: Coleoptera, beetlesFamily: Carabidae

Ground beetles are very abundant in mostagricultural and garden settings. "Whyhaven't I seen them?" you might ask. Well,most are nocturnal predators and spend theday hiding under rocks, at the bases ofplants and in soil crevices. Some species alsoclimb into trees, shrubs and crop plantslooking for prey. Adult ground beetles runquickly when disturbed but don't often fly.The adults and larvae are fierce predatorsthat chew up their prey with their large,sharp mouthparts. Caterpillars, grubs andadults of other beetles, snails, aphids, flymaggots and pupae, earthworms andother small soil dwellers are common prey

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Rove beetle

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for many ground beetles. They can consumetheir own body weight or more in food daily.

What you will see: Pick up a rock, siftthrough leaf litter or garden mulch, and youmight surprise some ground beetles, whichwill rapidly try to scurry away. Hundreds ofspecies of ground beetles occur in theMidwest. Adults have hard wing coveringsand vary in size from less than 1/4 inch tomore than 1 1/2 inches long. Most adults aredark brown or black, shiny and somewhatflattened, with slender legs for running. A few are an iridescent blue or green. Thelarvae are brownish, black with a large headand mandibles (jaws) and tapered. Groundbeetle larvae spend most of their timebelowground — you will be unlikely toencounter them. Their eggs are deposited

either on objects aboveground or in cavitiesmade in the soil. Ground beetles mayoverwinter as larvae or adults in soil.Typically, it takes one complete year todevelop from egg to adult, and they may livefor two to three years.

Caterpillar hunters: Ground beetles inthe genus Calosoma are called caterpillarhunters. They are large, usually 1 1/2 inches.Calosoma sycophanta, a large, brightmetallic green beetle, was imported fromEurope to New England for the biologicalcontrol of the gypsy moth in 1905. The larvafeeds day and night, consuming 50 cater-pillars during its two-week developmentalperiod. The adult will eat several hundredcaterpillars during a life span of two to fouryears.

Giving them a boost: Ground beetlesare highly susceptible to soil insecticides andfumigants. Because they need anoverwintering home, perennial plants (e.g., grassy areas) will give them aninsulated place to burrow during the cold.During the hot summer, ground beetles mustavoid water loss. They prefer to be in cloverground covers and mulches that provide ahumid microclimate. Ground beetles are notcommercially available but can easily beencouraged with garden mulches.


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Ground beetle

Ground beetle

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Put some soil in a fairly large container,about shoebox size. Put some rocks in onecorner and leaves in another; leave themiddle part with only bare soil. Nowcollect some live ground beetles withpitfall traps (see section on sampling) andadd them to this box. Leave them alonefor a while and then check where theyare. Where do they like to be? Checkthem at night — are they actingdifferently?

Feed the ground beetles caterpillars orpupae. If these are not available, throw insmall bits of cat food. Watch the groundbeetles eat. Notice the jaws, calledmandibles, cutting away the food. Arethey eating more than their body size?

thin abdomen. All have short antennae.There are many species which range in sizefrom less than 1/4 inch to more than 3/4inch long.

Females lay hundreds of tiny, white eggssingly on leaves or shoots near or amongaphid colonies through midsummer. Larvaehatch in three days and are small, leglessmaggots that range in color from creamy-white to green or brown. They may bemistaken for pests — they look somewhatsluglike and are tapered towards the head.The larvae complete their development intwo to three weeks while consuming up to400 aphids each. Depending on species, theymay pupate on the foliage or in the soil. Thesmooth, tan puparia are often teardrop-shaped. During the growing season, adultsemerge in one to two weeks. Generationtime depends on temperature, species andavailability of food; there may be five toseven generations per year. Hover fliesoverwinter as pupae.

Giving them a boost: Hover fly adultsare particularly attracted to Queen Anne'slace, wild mustard, sweet alyssum, coriander,dill and other small-flowered herbs. Havingthese plants will encourage females to lay

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Fun for Kids: Ground BeetleHomes and Dinner Time

Hover FliesOrder: Diptera, fliesFamily: Syrphidae

Hover flies are common and importantnatural enemies of aphids and other small,slow-moving insects. As their name implies,the adults are often seen hovering aroundflowers. Adults are not predaceous but feedon nectar and pollen and are important plantpollinators. Hover fly larvae feed mainly onaphids and also eat small caterpillars,thrips and other small insects.

What you will see: The adults mayresemble bees or wasps with black andyellow stripes on the body, but they haveonly one pair of wings (wasps have twopairs). Other hover flies are hairy with a long,

Hover fly life cycle

larval stages

eggpupa

adult

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eggs in your garden area. At this time, hoverflies are not commercially available.

— MBCN, v.2, n.11, Susan Mahr, Universityof Wisconsin - Madison.

Robber FliesOrder: Diptera, fliesFamily: Asilidae

Robber flies get their name from theirferocious manner of pouncing on their preyin the air. Adults are aggressive, generalisthunters, attacking butterflies, wasps, bees,dragonflies, grasshoppers, beetles and otherflies. Some of the larger species can inflict apainful bite if handled carelessly. Certainspecies frequently capture hornets or paperwasps, which are aggressive fighters. At leastsix species in North America feed principallyon grasshoppers. Most species, however,tend to feed more or less indiscriminately,destroying many destructive insects but alsobeneficial ones such as honeybees and otherpollinators. Robber fly larvae pierce the bodyof their prey and suck the body fluids fromthe wound. They generally feed on eggs orany soft-bodied insects that theyencounter, though some seem to specializeon grasshopper eggs or white grubs.

What you will see: Robber fly adults aremedium to large, hairy flies with anelongated, humped body and a slender,tapering abdomen. Most are gray, brown orblack, but a few species resemble bumble-bees. Adults live about three months. Thesefast and powerful fliers may produce a loudbuzz. They are able to capture in flight insectsmuch larger than they are. Adults never seemabundant because males are quite territorial.Any stray male that wanders into another'sterritory is either chased or captured.

Females deposit small, cream eggs on grassor other plants, soil, bark or wood. Eggs maybe laid singly or in large masses covered witha soft, chalky-white material. The small,cream-colored, cylindrical larvae live in thesoil or in decaying wood, migrating to locateprey. They overwinter as larvae and pupate inthe soil. The pupae come to the surface ofthe soil just before the adult emerges,leaving the pupal skin sticking out of the soil.Common species require one to three yearsto complete their development.

Giving them a boost: Adults requiresugar as well as protein before egg laying, sothey may be encouraged by planting nectar-producing flowers. Robber flies have notbeen used in biological control programs.Their role in natural control of pest specieshas not been well studied, even though theyare common in some areas.


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Robber fly

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SpidersClass: ArachnidaOrder: Araneae

Spiders may not be well liked, but they arehighly beneficial. About 15 families ofspiders are frequently found in crops, wherethey are natural control agents. Virtually anyactive stage of an insect's life cycle can fallprey to a spider, though each spider speciesis more likely to catch a certain prey type,because of its method of prey capture. Forexample, orb weavers are more likely tocapture adult flying insects than crawlinginsects.

How they find dinner: Many spidersconstruct a web of some sort to captureprey. Common families of web spinners arethe orb weavers (family Araneidae); thesheet web spiders (family Linyphiidae); thecomb-footed spiders (family Therediidae),which construct a very haphazard type ofweb; and the funnel web spiders (familyAgelenidae). Other spiders are known ashunters. These do not construct a web tocapture their prey, though they mayconstruct a silken refuge. These spiders arevery active and often run down their prey tocapture it. Their good vision helps themdetect movement of their prey. Examples ofhunting spiders include the wolf spiders(family Lycosidae), the jumping spiders(family Salticidae), the lynx spiders (familyOxyopidae) and the two-clawed huntingspiders (family Clubionidae). One largefamily, the crab spiders (Thomisidae),exemplify the ambush method of preycapture. These spiders are common onflowers and vegetation and sit motionlessuntil their prey comes within easy grasp.

Giving a them a boost: Chances are thatmany spiders are already present in yourgarden. You can help maintain theirpopulations by not using broad-spectruminsecticides. Insecticides not only directly killspiders but also kill many non-pest insectsthat the spiders use for food during periodsof low pest numbers. Spiders also need anoverwintering site; grassy perennials givethem a winter home.

No spiders have been successfully used innatural enemy importation programs(classical biological control), and none arecommercially available for augmentativereleases. However, there are a few examplesof human manipulation of spiderpopulations for improved natural control. InChina, bundles of straw are placed in fieldswith high spider populations. The strawprovides refuges, and the bundles can bemoved to relocate the spiders to other areas.

— MBCN, v.3, n.10, Dan Mahr, University ofWisconsin - Madison.

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Crab Spider

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Natural Enemies in Your Garden - Michigan Water Stewardship