The Fascinating Carpenter Bee
A few weeks back, during one of the warmer days of April, I was sitting on our back porch enjoying the spring air. What looked like a plump bumblebee was circling and darting about and then zoomed up close and hovered in front of me. After a few seconds of insect world stare down, it flew up onto the porch ceiling, walked along bare wood and disappeared into a small hole.
I would not have noticed the hole if I had not seen the bee, but sure enough, there it was, about ½-inch in diameter and just the right size for the portly insect to fit through. I said to myself “that’s no bumblebee, it must be a carpenter bee.” Since then I have made daily (and brief) observations of the fascinating carpenter bee. With a bit of research, I discovered they are another of our important pollinator insects, though definitely the first to take up residence in our house! Here’s what I found out.
Carpenter bees are about an inch long, and similar in appearance to bumble bees except the top of the carpenter bee’s abdomen is a shiny black color. You can tell the male from the female since it has a white dot on its head.
There are up to 500 species of carpenter bees worldwide and here in New England we have Xylocopa virginica, sometimes referred to as the eastern carpenter bee, with a range extending through the eastern United States and into Canada.
Carpenter bees are not aggressive, and the males don’t even have a stinger, but they are very territorial and will buzz you if you’re near where females are nesting. Females will sting if provoked.
Male carpenter bees release pheromones that attract females to them. Fertilized female carpenter bees then bore into wood, excavating tunnels and galleries to lay their eggs in individual chambers.
The female excavates a round, 1/2-inch hole into unpainted wood surfaces to create her tunnels. She uses her mouth and powerful mandibles to chew and drill the tunnel into the timber and then make a 90 degree turn into the wood. She “rasps” her mandibles against the wood and vibrates to tear the wood fibers in a circular pattern. The process creates sawdust (a good sign that you have carpenter bees) the female reuses when constructing individual partition chambers off the main tunnel for storing eggs.
Unlike the honey bee, they don’t make or store honey in their nests and instead regurgitate nectar and mix it with pollen to create a ball of thick “bee bread” they leave in the egg cells for the larva to feed on upon hatching. The eggs hatch and mature in about 36 days. The adult bee then begins foraging on flowers, returning to the tunnels to overwinter.
Anything made of wood on your landscape, especially unpainted softwood like pine, cedar or cypress are potential locations for carpenter bees to tunnel into. They don’t eat the wood for food and only chew into dead wood, or non-decayed limbs or trunks of standing dead trees.
Unlike honey and bumblebees, carpenter bees don’t live in colonies with a queen and prefer to live mostly solitary lives. Each female carpenter bee will mate and reproduce and overwinter individually, mostly in the brood tunnels where they also store pollen for the cold winter months.
As pollinators, carpenter bees are important for some open-faced or shallow flowers. They are excellent pollinators of eggplant, tomato and other vegetables and may be found foraging on a number of different species. They don’t have long tongues to reach deep into flowers and instead will cut a hole in the flower to reach the nectar.
Carpenter bees usually find their favorite sites for drilling holes on the unpainted underside of any wood surface including fascia boards, overhangs, soffits and window frames, and eaves. They are not thought of as true structural pest because they do not spread throughout the entire structure the way termites do.
Preventive maintenance is the best way to avoid the serious damage caused by these bees. Painting or applying wood varnish, caulking, and sealing off all crevices and spaces are suggested way to deter carpenter bees. Later this summer we plan on painting our house. After the carpenter bees have hatched and left their tunnels in our porch ceiling, we plan on filling the holes with ½ inch dowl and putty and applying a coat of paint to the unfished wood. While we appreciate their role as a pollinator, we prefer they take up residence somewhere else.
Carpenter bees are fascinating animals. With 500 species living in various habitats worldwide they play an important role as pollinators. Later this summer I’ll check my tomato and eggplant flowers to see if my resident carpenter bees are busy ensuring a good crop.
We live in a beautiful place called The Last Green Valley where every day is like having a National Park in our own backyard. Our region is home to many important pollinator insects, like the wood tunneling carpenter bee. I hope you’ll join me and others as we care for it, enjoy it, and pass it on.
Information for this column was sourced from the HoneybeeHQ website, UCONN Home and Garden Information Center, and the Clemson University Home and Garden Center. For information on important pollinators look for the upcoming 2021 spring/summer edition of TLGV’s InTouch magazine, available by calling 860-774-3300 of by download from the TLGV website.
Bill Reid is the Chief Ranger of The Last Green Valley National Heritage Corridor. He has lived in and explored the region for over 40 years and can be reached at firstname.lastname@example.org
Sign up for our newsletter