Order Coleoptera

Beetles

Beetle Collections

Beetle Collections

Beatle Collections

Coleoptera - Beetles

Largest of the insect orders40% of known species occur in

coleopteraAbout 30,000 species US and CanadaSizes from < 1mm to 125 mm (about 5”)

Coleoptera - Beetles

Many serious economic pestsHabitats vary greatly Beetles are found in most all situationsSubterranean, aquatic or semi-aquatic

Beetle Basics

Beetles have chewing mouthparts for chewing wood or crushing seeds

Beneficial varieties attack insect pests and others act as scavengers

Scobicia declivis the lead-cable borer is capable of boring through the lead sheathing of telephone cable

Scobicia declivis

Beetle Basics

Most beetles have 2 pairs of wingsThe front wings or Elytra are leathery or

hard and brittleThe hind wings are membranous and are

folded under the elytraThe hind wings are the wings used for

flight

The Elytra

The Elytra

The Elytra

The Elytra

Feed the Beetle

Feed different plant and animal materialsPlant eaters, predators, scavengers, eat

fungi or molds; very few are parasitesPlant eaters – feed on foliage, fruits, nuts,

flower, wood borers, some attack roots

Feed the Beetle

Others eat stored plant and animal products, clothing, leather, various fabrics, and various other organic materials

Feed the Beetle

Beetles undergo a complete metamorphosis

There are several variations in the larval form

Life cycles vary from 4 generations per year to one generation in several years

Feed the Beetle

Most species – one generation per yearThey may overwinter in any life stageLarvae have 6 legs

Family Scarabaeidae

Scarab Beetles

Scarab Beetles

Family ScarabaeidaeAbout 1,400 species in

North AmericaVary greatly in shape,

size and colorSome incredible metallic

shadesHeavy-bodied Oval to elliptical in

shape - convex

Plusiotis chrysargyreae

Scarab BeetlesVaried habitsFeed on dung,

carrion, decomposing plant materials

Live in nests or burrows of vertebrates, or ant or termite colonies

Giant Dung Beetle

Dung Beetle Crossing

Scarab Beetles

Feed on live plant materials – fruit, flowers, foliage, grasses

Serious pests to turf, golf greens, ag. crops

Larvae are ‘C’-shapedLarval form is damaging

life stage

‘C’-Shaped Larvae

Scarabs

Adult Japanese Beetle Japanese Beetle Larvae

Popillia japonica Newman

Scarabs

Fig Beetles

Cotinis texana

Scarabs

10 Lined June Beetle

Chafer BeetleAmphimallon solstitialis

Polyphylla decemlineata

Family Scolytidae

Bark Beetles

Bark Beetles

Family ScolytidaeThe three most

important genera include: Dendroctonus, Ips and Scolytus

Bark beetles – small, cylindrical beetles <8mm

Usually brownish or black Itty-Bitty Beetles

Bark Beetles

Bark beetles can be divided into two groups

Bark beetles – feeds on inner bark and succulent wood

Ambrosia beetles – feeds ambrosia – fungus they cultivate

Ambrosia Fungus

Bark Beetles

Ips species Beetle

Bark Beetles

Lives within the bark, feeds at the surface of the wood on the phloem tissue

“Engravers” – Ips and Scolytus spp. which cut deeply into the sapwood

Scolytidae Galleriesw/ an “Engraver’s” path in

the center

Bark Beetles

Bark beetles feed on dying trees

Some species infest and kill living trees, particularly conifers

These trees are typically under physical stress Trees Killed By Bark

Beetles

Bark Beetles

Three species of scolytid beetles merit the most economic importance:

DendroctonusIpsScolytus

Dendroctonus

Dendroctonus ponderosae

Ips

Ips sexdentatus

Scolytus

Scolytus ratzburgi

Bark Beetles

Fungus is “blue-stain” or “brown-stain”

Adults introduce fungi, larvae spread it

Fungus clogs the water transport vessels

Sap or pitch production is suppressed

Blue-Stain Fungus

Bark Beetles

Bark beetles can overwhelm a tree’s natural defenses by their sheer numbers

Adults respond to a combination of odors emitted from the resin from the potential host tree and chemical signals (pheromones) from the first colonies

The result – thousands of beetles may infest a tree simultaneously

Bark Beetles

Species of bark beetles can either be monogamous or polygamous

In monogamous species the female bores the initial hole in the tree

The male clears the frass behind herThe female lays her eggs in notches

along the sides of the gallery

Bark Beetles

The eggs hatch into ‘C’-shaped larvaeThe larvae begin boring at right angles to

the gallery As the distance increases from the main

gallery the “larval mines” become larger and begin to fan out

The larvae pupate at the ends of the mines

Larvae Galleries

Bark Beetles

The new adult beetles emerge through round holes bored through the bark

After the brood emerges the tree appears to have been peppered with “shot” holes

“Shot” Holes in Bark

Bark Beetle Impact

Bark beetles have a greater impact on North American forests than any other insect

Singularly responsible for the death of more than 4 billion board-feet of timber annually

Over 90% of the insect caused mortality

Bark Beetle Impact

5 species of bark beetle responsible for most of the damage

Southern Pine Beetle (Dendroctonus frontalis)

Douglass Fir Beetle (D. pseudotsugae)Mountain Pine Beetle (D. ponderosae)Western Pine Beetle (D. brevicomis)Spruce Beetle (D. obesus)

The Evidence

Recognized by fading foliage colorNoticeable in groups or stands of treesFrass or hardened pitch-tubes on the

barkLarge amounts of woodpecker activityBark beetles are host specificGalleries are characteristic to each

species

Frass on Exposed Galleries

Infested Trees

Dutch Elm Disease

Spread by the European Elm Bark Beetle (Scolytus multistriatus)

Probably introduced into Europe from Asia around WWI

Thought to have entered the United States in the 1920s

It was first reported in Ohio in the 1930sIt has since spread across most of North

AmericaThe American elm has been almost completely

eliminated from the urban landscape

Dutch Elm Disease

Ambrosia Beetles

Feed in live or freshly killed treesThe fungus they cultivate stains and

reduces the value of woodLarvae and adults share galleriesAdults care for larvae and feed them on

the ambrosia fungusAdults move to new trees carrying

conidia of fungus to infest new trees

Ambrosia Beetle Damage

Wood Staining