Carpenter bees drill neat holes in timber but never eat the wood
That perfectly round hole, about 16 millimetres across, under a porch beam or garden bench is usually a carpenter bee's front door. The big, buzzing bee hovering nearby looks menacing, but if it is a male it has no sting at all, and even the females rarely use theirs.
Carpenter bees make up the genus Xylocopa, Greek for wood-cutter, with about 500 species. Almost all nest by boring into dead wood, bamboo or tough plant stems, vibrating their bodies while rasping with their jaws. They do not eat the wood; they throw out the shavings or reuse them to build walls between cells. Inside, each cell is stocked with an intricately shaped lump of pollen and nectar, sculpted with projections that hold it away from the walls. Their eggs are enormous relative to the mother, among the biggest laid by any insect.
People often mistake them for bumblebees. The easy test is the abdomen: most carpenter bees have a shiny, largely bare one, while bumblebees are fuzzy all over. Many species are almost impossible to tell apart except by tiny anatomical details, and in India any all-black carpenter bee tends to be called by one local name and wrongly pinned on a European species that lives only in the far north.
Traditionally they count as solitary bees, but some species share nests between mothers and daughters, dividing the work so one forages while others stand guard. Males find mates in one of two ways. Big-eyed males patrol or hover in wait for passing females, while small-headed males release scent from a large gland into the air behind them as they fly.
They matter as pollinators. The maypop, a North American passionflower, depends on them, since no other insect does the job. Yet their short mouthparts also make them nectar thieves: on long, tubular flowers some species slit the side to drink without touching the pollen. Woodpeckers, drawn by the noise of larvae inside the tunnels, often cause more damage to timber than the bees themselves.
Source: Carpenter bee
