Carpenter Bees Are Officially Here

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What could be more frustrating than japanese beetles, boxelder bugs or army worms? The answer is carpenter bees. Anyone who owns a building made of wood is probably experiencing the problems of trying to deal with these large, hovering, persistent and destructive insects right now.

Any exposed wood surface is a potential target for the carpenter bee which looks similar to a bumble bee. They do not, however, eat the wood like termites, they only excavate tunnels for nesting purposes. They also overwinter as adults in these nesting tunnels and come out in the spring, usually April and May. This year they are early. We spotted the first one at our office on March 14. After emerging in the spring, carpenter bees feed on nectar for a few weeks and then begin to make new tunnels for laying their eggs. This is when most damage occurs.

The female makes a large pollen ball in the tunnel for feeding her young and then lays eggs until the tunnel is full. The adult bees die soon afterward and in a few days the eggs hatch and young bees emerge and begin to feed on the pollen ball provided for them. They grow into adults in five to seven weeks. These carpenter bees cause no more damage but do overwinter in the same tunnels. The following spring they will begin to excavate new tunnels for laying their eggs and the cycle starts over again.

Controlling the damage done by carpenter bees is very difficult. They do not eat  wood so chemicals sprayed on wood have very little effect. Spraying bees as they are hovering is not a practical option either and certainly not a safe practice. Treating the entrance holes to the tunnels does seem to give some control. Products containing carbaryl, cyfluthrin or resmethrin can be sprayed in the holes. Twenty four to thirty six hours later these holes should be sealed with caulk. The insecticide will kill both adult and young bees. Caulking without spraying does very little good because the bees will just tunnel out somewhere else. It is important to caulk these holes because they can be used again next year.

There is a lot of work involved in controlling carpenter bees and even then, not all of the bees will be gotten rid of. It will, however, limit the damage done by these destructive insects.