I saw my first carpenter bee of the season and I’m ready to continue the battle. Many years ago Mary Alice had a garden shed built in our back yard. Several years later a few carpenter bees found the shed to be an excellent place to build nests.

At first I was not alarmed and did nothing. A few years later, however, Mary Alice told me that the carpenter bees were boring lots of holes in her garden shed. That was when the big bee battle began.

The carpenter bee found in our area resembles the common bumblebee. However, the carpenter bee has a shiny, bluish-black abdomen whereas the bumblebee has a hairy abdomen that is mostly yellow.

Bumblebees are social insects, meaning the bees work together for the welfare of the colony. On the other hand, the carpenter bee is a solitary bee. Usually, it is the social insects that sting.

The female carpenter bees excavate their nests in wood, hence the common name of carpenter. A nest consists of a round entrance hole about one-half inch in diameter and about one-inch deep. After the hole is drilled, the bee makes a 90-degree turn and bores with the grain, making a tunnel that is from six inches to several feet in length. The female builds the nest at the rate of one inch in six days.

These nest tunnels are cleaned, enlarged and used year after year by many generations of carpenter bees. Some nests have been known to be used for as long as 14 years. Once a population is established they are hard to get rid of.

Inside the nest tunnel, the female prepares a series of brood cells, providing each cell with bee bread, which is a mixture of pollen combined with regurgitated nectar. The female places an egg in the cell, builds a partition of chewed wood, continues to make another cell with food and then lays an egg in this cell. Most females will produce six to eight of these cells.

Inside the cell, the eggs hatch into larvae, feed upon the bee bread and then change into a bee. This cycle takes 30-40 days to complete. In August, the young bees will begin to emerge from the nest. The egg laid in the first cell is first to hatch, with the larvae becoming the first bee. This bee must chew through all the partitions placed by the female between each cell and then crawl over the other developing bees.

There is only one generation of young, and they fly about feeding on nectar. As cold weather approaches, the young return to the tunnel nest to over-winter. The older adult bees will die at the end of the summer. The young bees will emerge in the spring, usually in April or May, however this really depends on the temperature, which needs to reach into the 70s for the bees to become active.

Once out of the nest mating — which is accompanied by a strange bobbing dance by the male — will begin. After mating the female will either build a new nest tunnel or enlarge and reuse an old nest. The only way one can tell whether a nest is active or not is if fresh sawdust is found beneath the entry hole.

The female does all of the nest building. She prefers to bore in either weathered or unpainted wood, and usually, for the nest to have a southern or eastern opening. These nests seldom cause structural damage but trim and decorative wood are often damaged. Common nest sites include eaves, window trim, facia board, siding and wooden shakes. The buzzing flights of the adults attract woodpeckers, which will bore into the wood to get at the larvae in the cells. Also, one will find the female’s waste material, which leaves an unsightly stain, beneath the entry hole.

A male carpenter bee has a white marking on its head. It is the aggressive male’s job to protect the nest and if you get too close to the nest, he will hover around your head. A common behavior of the males is to approach people if they move too quickly or wave their hands in the air. At times, the males hover a short distance from people, causing unnecessary panic. However, males are harmless because they do not have stingers and thus cannot sting. On the other hand, females can and do inflict painful stings, but seldom do unless they are handled. Even though I know that carpenter bees do not sting, when a bee began flying around my head I began flailing my arms and made a hasty retreat.

Carpenter bees are not particularly important as pollinators. If the carpenter bee cannot reach the nectar at the base of tubular flowers in the regular way, a hole is made at the side of the flower to get at the nectar.

After the female completes and seals her last egg cell, she will take life a little easier, sipping nectar until cold weather takes her life. Life is also easier for the male after the nest is sealed because protection is no longer needed.

Control of the carpenter bees can be done with insecticides that are labeled for bees or wasps. The entrance hole should be sprayed at night, with the aid of a flashlight, over which a piece of red cellophane has been placed. Wait a few days for the female to become exposed to the pesticide, and then, plug the hole with either plastic wood, putty or a wooden dowel.

The best time to do this is in the spring when the female is just starting to build a nest. If it is done later in the summer (August), you will need to spray again as the juvenile bees start to leave the tunnel nest and then again, at the end of September, when the young are returning to the nest to over-winter.

I never paid too much attention to the carpenter bees until they caused a problem in Mary Alice’s garden shed.

Bill Bower is a retired Pennsylvania Game Commission Wildlife Officer. Read his blog and listen to his podcasts on the outdoors at www.onemaningreen.com.