Toward the end of June, my wife, Mary Alice, called my attention to a small pile of sawdust on the ground beneath a cellar window. On checking, I discovered that carpenter bees had been boring holes in the unpainted window frame.
Many people who complain about bumblebees flying about under the eaves of their homes actually are seeing carpenter bees.
The carpenter bees (Xylocopa virginica) found in our area resemble the common bumblebee. However, the carpenter bee has a shiny, bluish-black abdomen whereas the bumblebee has a hairy abdomen that is mostly yellow.
PHOTO COURTESY OF BILL BOWER
These holes were made by carpenter bees in Mary Alice Bower's unpainted garden shed.
PHOTO COURTESY OF BILL BOWER
Carpenter bees are making their homes in Mary Alice Bower’s garden shed, much to her dismay.
Bumblebees are social insects and work together for the welfare of the colony, while the carpenter bee is a solitary bee. Usually, it is the social insects that sting.
The 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, he will hover around your head.
Although the male's common behavior is to hover a short distance from a person, the male bees will approach if the person unnecessarily panics and moves too quickly or waves their hands in the air. Males are harmless because they do not have stingers; however, females can and do inflict painful stings but seldom do so unless they are handled or molested.
A female carpenter bee excavates its nests in wood; hence, the common name of carpenter. A nest consists of a round entrance hole about 1/2-inch in diameter and about 1-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 6 inches to several feet in length.
The female builds the nest at the rate of 1 inch in six days.
Unpainted wood usually is attacked and wood that is greater than 2 inches thick is preferred.
The 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.
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. After the female places an egg along with the bee bread food in the cell, she builds a partition of chewed wood and then continues the process until there are six to eight cells.
After the eggs hatch into a larvae, they feed upon the bee bread and then become bees. The cycle takes 30 to 40 days to complete. In August, the young bees will begin to emerge from the nest.
The egg laid in the first cell will hatch first, with the larvae becoming the first bee. The first bee must chew through the partitions between each cell and then crawl over each of the other developing bees.
There is only one generation of young and all they will do is fly about and feed 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.
Depending on the temperature, which needs to reach the 70s for bees to become active, the young bees will emerge in April or May.
When out of the nest, the male will begin mating, which is accompanied by a strange bobbing dance. After mating, the female either will build a new nest tunnel, enlarge or reuse an old nest. The way one can tell whether a nest is active or not is to check for fresh sawdust beneath the entry hole. Also, the female's waste material, which leaves an unsightly stain, can be found beneath the entry hole.
The nest will have either a southern or an eastern opening. Although these nests seldom cause structural damage, damage is done to trim and decorative wood. Common nest sites include eaves, window trim, fascia board, siding and wooden shakes. The buzzing flights of the adult bees attract woodpeckers, which will bore into the wood to get at the larvae in the cells.
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 also is easier for the male after the nest is sealed because protection of the nest is no longer needed.
Carpenter bees can be controlled with insecticides labeled for bees and wasps. A dust is better than a spray because the spray will penetrate the wood, while the dust will continue to have contact with the bees as they enter and exit the hole.
We share this planet with insects that lead interesting and fascinating lives and, for the most part, their activities go unnoticed by man. That is until they cause us some kind of problem or buzzing around our heads. Then, they have our full attention.
Bower retired after 34 years as a wildlife conservation officer for the state Game Commission. He has published several books about his experiences. Questions and comments may be sent to him at 153 Redington Ave., Troy PA 16947.