Eastern Carpenter Bee

the difference between a carpenter bee, xylocopa virginica, and a bumble bee. from wilkipedia:

the most visible physical difference is the abdomen. eastern carpenter bees have a shiny black abdomen, with the only yellow hair present being at the base next to the thorax, while bumblebees have a very fuzzy abdomen, which in some species has large areas of yellow hair across the middle (this is visible and obvious). also, the carpenter bee has large compound eyes. the female eastern carpenter bee also has a much broader head than bumblebees. eastern carpenter bees can be sexed at a glance. males have a patch of white cuticle on the face, as opposed to females, whose faces are black. males are unable to sting.

female carpenter bees make nests by tunneling into wood. they make an initial upward hole in an overhang, eaves trough, or similar structure. then, they make one or more horizontal tunnels. the final nest usually resembles a t. unlike termites, carpenter bees (also called woodcutters) do not eat wood. they discard the bits of wood, or use them to make partitions (walls) inside the tunnels of their nests. the tunnel functions as a nursery for brood and the pollen/nectar upon which the brood subsists.

males will visit flowers only to feed themselves, spending the rest of the time hovering in their territory and investigating any movement, or guarding flowers where they might encounter females . females spend the majority of their time gathering nectar and pollen to provision their nests.

because of their value as pollinators some people allow carpenter bees to stay around the home in the early spring, living with the cosmetic damage caused. in some fruit growing areas carpenter bee populations are encouraged by supplying them with suitable blocks or boards of soft wood.

in the eastern u.s., xylocopa virginica overwinter as adults inside the same tunnels where they hatched that summer. in spring, they awaken. the males hover around looking for mates. the female enlarges the existing tunnel, or moves nearby and bores a new tunnel. she creates separate partitions in the tunnel out of sawdust and saliva. she provisions each section with a paste-like wad of pollen and nectar, lays one egg on it, and seals it off. she makes many of these partitioned cells, with as few as 1 and in excess of 20. the egg hatches into a grub-like larva which eats the pollen mass. it then turns into a pupa, which hatches into an adult bee in mid- to late summer. the newly hatched adults break through the partitions and crawl over each other to escape to the outside world. however, they do not then disperse, but continue to live in the tunnel, preparing to hibernate. thus, the piece of wood is inhabited by bees year-round.

rarely, active nests in a home can involve considerable damage, but woodpeckers normally are the primary cause of it, as they search out larval bees.

carpenter bee nests are rather easy to spot. they bore a highly polished hole about 1cm in diameter directly up into the bottom a nesting substrate (usually an eave, picnic bench or similar wood structure). when the female is boring tunnels, there is a collection of fresh sawdust below the hole and the sound of boring can be easily heard. one can often see yellowish splashes of waste below the entrance, produced by the bee just as she flies out.

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