Thursday, April 29, 2010

'Tis the Season - Seeing Sawdust Below Your Roof or on It?

Every year during late April, we'll get a real warm day and all of a sudden you may some huge bumblebee like creatures flying around your house, especially the roof line. You may about to be infested by Carpenter bees (see picture on the right). These gentle creatures (the females can sting, but I challenge anyone to get one to do it) tunnel into wood. They emerge from winter dormancy in late April here in the Northeast. They proceed to go about their mating flights. They fly around, hover in one spot, and chase each other around, and finally mate. After mating, the males die. The females then go about drilling their holes.As you can see from the picture, one of their favorite spots to drill their holes is in back of the trim board that runs along the edge of the roof. Each bee is a solitary nester, meaning there is not a "nest" containing more than one (other than the young). They drill a half inch round hole about half way through the board and then turn at right angles and drill a tunnel 6-7 inches long, leaving a pile of sawdust on whatever is under their hole. Sometimes they will drill holes right into the face of log homes. They prefer unpainted wood. Most people with normal hearing can actually hear them chewing the wood. They lay eggs in the tunnel and provide those eggs with "bee bread", a mixture of pollen and nectar from flowers. Each egg is sealed in separately and after the female is done with her egg laying, she dies. This usually occurs by the end of the first week in June, so their "season", when active drilling is occurring is only about 6 weeks long. The young emerge as adults later in the summer and spend the rest of the summer foraging on flowers (they are great pollinators). The young may overwinter in the holes they were "born" in. As  you can see from the picture they leave a tell tale droppings stain right under the entrance to their tunnels. The holes on the outside of the board are made by woodpeckers looking for the nice juicy larva growing inside the tunnels in the wood. This damage is the most significant damage done. They do no structural damage. Their damage is purely cosmetic. They can be killed with pesticides, but the most permanent solution is to physically exclude them. Depending on the situation (and it is not always possible to do this), this can be done with paint, flashing, hardware cloth, or anything that will prevent them from accessing the area where they want to drill their holes.