by Whit Gibbons

April 1, 2007

Every year at this time I get questions about bees. Recently, a friend told me about honeybees swarming on a university campus. She and her fellow employees gathered to watch as the bees flew around the office windows then collected in a huge clump on a nearby tree. The bees were still there the next day when my friend got to work, but 20 minutes later they had disappeared. Not a bee was to be seen. What was going on?

A queen and several thousand workers were simply looking for a new home. The bees hang in a large cluster while scouts look for a place to start a new hive. Honeybees have declined across the United States since the 1990s because of parasitic mites. So a swarm is a healthy sign that a nearby hive has become overcrowded and some bees have left.

Honeybees typically do not sting during the swarming stage. My son and I once put a cardboard box with a hole in it next to a swarm and let the bees crawl over our hands as they walked inside to set up a new colony. We took the box of bees home, put them in a wooden box, and a couple of years later actually ate honey they produced.

Another bee question concerns tiny piles of sawdust from unpainted wooden structures. The sawdust is caused by carpenter bees that burrow into the wood. Carpenter bees are similar in appearance to bumblebees. A common question is, how can I get rid of them? My answer is do not get rid of them. Enjoy them. On our back porch, instead of eradicating them, we watch them, listen to them, and smile as the dog snaps at them. Cheap entertainment on a spring day.

The ecology of carpenter bees is relatively straightforward. In spring, throughout most of the country, they seek mates. Males, which have a distinctive light-colored spot on the face, may buzz loudly and fly in front of a person’s face. But the bluster is just an act. Male carpenter bees are harmless. As with other bees and wasps, only the females have stingers. I grabbed a male bee last week and held it. It was mad when I let it go but did not sting.

Female carpenter bees literally chew a tunnel into wood. I know they work at night as well as day because I have watched a steady stream of sawdust trickle from the ceiling an hour after dark. The females prefer an already created hole, but some additional excavation and reorganization may be part of the process, much like someone moving into a new apartment might paint the walls or rearrange the furniture. Sitting beneath a carpenter bee reconstruction project leads to frequent brushing of sawdust from your clothes.

Carpenter bees are valuable pollinators--females gather pollen, store it in the burrows, and lay their eggs. The pollen serves as a source of nutrition for the larvae. The adult bees die during the summer, and the recently born ones spend the winter in the holes.

How harmful is a carpenter bee? A female carpenter bee could sting you. But a person generally has to grab one to be stung; they rarely attack like bumblebees defending their nest or like wasps. Using pesticides to destroy carpenter bees is unnecessary, and pesticides never kill just the target organism but many other harmless creatures as well.

Could burrowing over the years cause structural damage that might weaken a porch roof? Maybe, but since carpenter bees make it simple on themselves by using holes that have already been constructed instead of creating new ones, demolishing an entire structure would take a lot of burrowing. Our porch may eventually fall down from the annual attack of the carpenter bees, but if it does we will have gotten considerable entertainment from these fascinating creatures for many, many years.

To me the potential hazards of carpenter bees--and a lot of other animals that some people seem suspicious of--are not worth controlling with pesticides. It's too high an environmental price to pay. Far better simply to enjoy nature, whether it appears as carpenter bees on your back porch or a swarm of honeybees outside your office window.

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