Eastern Carpenter Bee
The Eastern carpenter bee (Xylocopa virginica) is a pest due to the small round holes it drills into unprotected wood surfaces and because it is often confused with bumble bees when the males charge at nearby people. Active in early spring, carpenter bees continue to drill holes throughout the summer as they provide multiple nests to rear their young.
The Eastern carpenter bee looks a lot like a bumble bee. Both are large black bees with a yellow hairy thorax and a black gaster. Carpenter bees do not have a bright orange pollen sac on the base of their hind legs and bumble bees do. Carpenter bees have a very shiny smooth black gaster and bumble bees have their gaster covered with fine hairs. You have to be close to visually see this character.
You can use behavior to more easily separate these two different insects. Carpenter bee males fight each other for control of females and if you watch carefully you can see males in aerial combat chasing off competitor males. The males are so aggressive when protecting a female bee that they will swoop down and dive bomb any person standing or passing nearby. Since the males do not have a stinger, this attack is a bluff and you are not in danger.
More importantly, female carpenter bees drill small round holes in exposed wood while bumble bees pollinate flowers. The carpenter bee nest holes are round and smooth as if created by a drill and there is a small pile of sawdust on the ground directly below the entrance hole.
Carpenter bees over-winter as adults inside of the galleries made the previous year. They mate and females begin to drill new nest holes in early spring. The female bee first drills directly into the wood a short distance and then changes direction and continues to drill her hole for a foot or more in a right angle direction. Once her nest gallery is complete, she searches for pollen and nectar and makes a small packet and stuffs it in the end of the gallery. Next she lays an egg on the pollen/nectar packet and seals up the chamber with a thin divider of wood debris. She will make several of these packets with partitions and may drill several nest holes.
The eggs hatch and the grubs feed on the pollen and nectar until mid summer. Once the grub changes into an adult bee it crawls out to the entrance hole but does not disperse. Instead it prepares to hibernate for the winter in the same tunnel.
Carpenter bees prefer to tunnel into unpainted and otherwise exposed wood surfaces. This wood surface could be the sides or eaves of a home, a fence post or fence slat, and any block of soft wood. If you are close by you can hear the female cutting her tunnel and can see her dumping the fresh sawdust below.
Getting rid of carpenter bees is difficult because they often nest high above ground in the eaves of homes. And new bees can fly into the same area each year requiring repeated control efforts. Prevention of carpenter bee damage is more practical and a more long-term solution.
1) Paint over exposed wood on the side of your home. Make sure to paint on the underside and edges of eaves as this area is commonly exposed to carpenter bee attack. Staining wood may not be as effective as paint. Flashing and screen will protect wood if installation of these materials is possible.
2) If you see active carpenter bees tunneling and you want to prevent further damage you could place a small wad of fine mesh screen inside the entrance and seal the entrance with a three/eighths plug of hard wood.
3) If you are interested in nature and understand that female carpenter bees pollinate flowers during their search for nectar and pollen and are beneficial, you could set up a sacrificial section of soft wood nearby in the hopes that the bees would drill in this block of wood rather than your home.
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