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Plant Industry - Structural Pest Seasonal Pest Problems

CARPENTER BEES

Lifecycle 

Carpenter bees are large, robust, insects that resemble bumble bees.  Carpenter bees may be distinguished from bumble bees by looking at their abdomen.  Bumble bees have a hairy abdomen while carpenter bees have a hairless, black shiny abdomen.

Carpenter bees can become a nuisance by boring into the wood in houses during the spring.  The female carpenter bee chews tunnels into wood, often up to several inches long, where she will make cells to lay her eggs.  Each cell is lined with nectar and pollen and separated by partitions made of chewed wood.  Only one egg is laid in each cell.  Adult carpenter bees emerge in late summer, each waiting in line to exit the tunnel.

Control

Control of carpenter bees is difficult.  Any exposed wood is susceptible to attack.  Wood that has been newly painted is less likely to be attacked by carpenter bees, however, painting does not make the wood immune to attack.  Carpenter bees are best controlled by treating individual tunnels.

Homeowners should try to control the insects whenever they are observed boring into wood around the home.  Dusting around the entrance to the tunnel with 5% Sevin dust is an effective control method.  Sevin is an insecticide that is highly toxic to bees.  The insect will come into contact with the insecticide when it tries to enter the tunnel and it will kill the insect when it attempts to groom and clean its body.

It is not recommended that holes be plugged until late summer.  There may be some eggs in the tunnels and the adults will unplug any holes when they emerge.  Plug tunnels in late summer or fall, when the bee have emerged.  It is essential that bee tunnels be plugged.  If tunnels are not plugged, carpenter bees may use the tunnels again next year. 

IMPORTANT:  READ AND FOLLOW ALL LABEL DIRECTIONS AS IMPROPER USE OF INSECTICIDES MAY AFFECT ANIMAL AND HUMAN HEALTH.