7/30/2019 Carpenter Bees

1/2

PESTNOTES Publication 7417University of California

Agriculture and Natural Resources Revised February 2004

CARPENTERBEESIntegrated Pest Management in and around the Home

Carpenter bees build nests in wood,creating galleries that can weaken struc-tures; however, they rarely cause severedamage. People may be frightened bycarpenter bees because of their largesize, their similarity to bumble bees, andtheir annoying noise.

IDENTIFICATIONMost carpenter bees, Xylocopa spp., arelarge and robust insects (Fig. 1) resem-

bling bumble bees. They are usuallyabout 1 inch long and colored a metallic

blue-black with green or purplish reflec-

tions. They differ from bumble bees inthat their abdomen is shiny with fringesof hairs on some segments. Males ofsome species are lighter colored, rang-ing into golden or buff hues.

LIFE CYCLEFemale carpenter bees bore intosound wood or sometimes into decay-ing wood to make nests. Nests usuallyconsist of tunnels 1/2 inch in diameterand 6 to 10 inches deep that are parti-tioned into several chambers, each con-taining an egg and a supply of food(pollen). Carpenter bees may use oldtunnels for their nests, which theysometimes enlarge; several bees mayuse a common entry hole connecting todifferent tunnels. Over a period of time,tunnels may extend as far as 10 feet intowood timbers. Tunnels are vacated afterthe broods larval and pupal stagescomplete their development. Develop-ment from egg to adult may take about3 months. Carpenter bees overwinter asadults, often in old tunnels, and there isonly one generation a year.

DAMAGECarpenter bees cause damage towooden structures by boring into tim-

bers and siding to prepare nests. Thenests weaken structural wood and leaveunsightly holes and stains on buildingsurfaces. Sound, undecayed wood with-out paint or bark is usually selected fornests. Carpenter bees also frequentlyattack dead wood on trees or lumberfrom southern yellow pine, white pine,California redwood, cedar, Douglas fir,cypress, mimosa, mulberry, ash, andpecan trees. They avoid most harderwoods. The presence of carpenter beesaround buildings and wooden struc-tures can be annoying or even frighten-

ing; however, males cannot sting andfemales rarely attack.

MANAGEMENTPrevention is the main approach tomanaging carpenter bees. If possible,susceptible exterior parts of a buildingshould be constructed out of hard-woods not normally attacked by the

bees for nests. On all buildings, fill de-pressions and cracks in wood surfacesso they are less attractive. Paint or var-nish exposed surfaces regularly to re-duce weathering. Fill unoccupied holeswith steel wool and caulk to preventtheir reuse. Wait until after bees haveemerged before filling the tunnels. Oncefilled, paint or varnish the repairedsurfaces. Protect rough areas, such asends of timbers, with wire screening ormetal flashing.

Carpenter bees are generally consideredbeneficial insects because they helppollinate various crop and noncropplants. Under most conditions they can

be successfully controlled using thepreventive measures described above.If infestation is high or risk of damageis great, insecticides may be used toaugment other methods of control. To

do this, treat active nests (those contain-ing eggs, larvae, or pupae) with liquidor dust formulations of insecticides ordesiccant dusts. Liquid formulationscontaining permethrin and cyfluthrinand dusts containing boric acid arecurrently labeled for use against car-penter bees. Desiccant dusts are inertdusts combined with absorptive pow-ders (diatomaceous earth or boric acid)that destroy insects by abrading theirprotective outer body cover, causingthem to dry out. Desiccant dusts arelow in toxicity to people and animalsand do not lose their effectiveness overtime, so long as they do not get wet.Avoid inhaling these materials, how-ever, because they can cause seriouslung irritation.

After the brood is killed, repair holeswith steel wool and wood filler, thenrepaint or varnish the repaired surfaces.

COMPILED FROM:Marer, P. 1991. Residential, Industrial,and Institutional Pest Control. Oakland:Univ. Calif. Agric. Nat. Res. Publ. 3334.

(actualsize)

Figure 1. Carpenter bee adult.

7/30/2019 Carpenter Bees

2/2

2

February 2004 Carpenter Bees

For more information contact the University

of California Cooperative Extension or agri-

cultural commissioners office in your coun-ty. See your phone book for addresses and

phone numbers.

TECHNICAL EDITOR: M. L. Flint

COORDINATION, DESIGN, AND

PRODUCTION: M. Brush

ILLUSTRATION: David Kidd

Produced by IPM Education and Publica-

tions, UC Statewide IPM Program, Universi-

ty of California, Davis, CA 95616-8620

This Pest Note is available on the World

Wide Web (http://www.ipm.ucdavis.edu)

This publication has been anonymously peer re-viewed for technical accuracy by University of Cal-ifornia scientists and other qualified professionals.This review process was managed by the ANR

Associate Editor for Pest Management.

To simplify information, trade names of productshave been used. No endorsement of named productsis intended, nor is criticism implied of similar productsthat are not mentioned.

This material is partially based upon worksupported by the Extension Service, U.S. Departmentof Agriculture, under special project Section 3(d),Integrated Pest Management.

WARNING ON THE USE OF CHEMICALSPesticides are poisonous. Always read and carefully follow all precautions and safety recommendations

given on the container label. Store all chemicals in the origina l labeled containers in a locked cabinet or shed,away from food or feeds, and out of the reach of children, unauthorized persons, pets, and livestock.

Confine chemicals to the property being treated. Avoid drift onto neighboring properties, especiallygardens containing fruits or vegetables ready to be picked.

Do not place containers containing pesticide in the trash nor pour pesticides down sink or toilet. Eitheruse the pesticide according to the label or take unwanted pesticides to a Household Hazardous WasteCollection site. Contact your county agricultural commissioner for additional information on safe container

disposal and for the location of the Household Hazardous Waste Collection site nearest you. Dispose ofempty containers by following label directions. Never reuse or burn the containers or dispose of them in sucha manner that they may contaminate water supplies or natural waterways.

The University of California prohibits discrimination against or harassment of any person employed by orseeking employment with the University on the basis of race, color, national origin, religion, sex, physicalor mental disability, medical condition (cancer-related or genetic characteristics), ancestry, marital status,age, sexual orientation, citizenship, or status as a covered veteran (covered veterans are special disabledveterans, recently separated veterans, Vietnam-era veterans, or any other veterans who served on activeduty during a war or in a campaign or expedition for which a campaign badge has been authorized).University policy is intended to be consistent with the provisions of applicable State and Federal laws.Inquiries regarding the Universitys equal employment opportunity policies may be directed to theAffirmative Action/Staf f Personnel Services Director, University of California, Agriculture and NaturalResources, 300 Lakeside Drive, 6 th Floor, Oakland, CA 94612-3550, (510) 987-0096.