QUESTION:

I have a house that has carpenter bees that we have treated. However, now the customer is saying that woodpeckers are digging into the wood of the house to get the larvae. What can I do to, and is there anything that will help?

ANSWER:

I thought about this a few minutes, and it suddenly dawned on me that there should not be any bee larvae in the wood at this time, if you have normal-acting carpenter bees. The typical biology of carpenter bees is for the adult bees to be the stage that over-winters in the chambers in the wood, and if you feel you have already dealt with the adult bees then no living insects would be in those old channels to pique the interest of the woodpeckers. However, perhaps your control did not manage to get deep enough into the chambers to kill all the overwintering bees, or they managed to hole up in there before you recognized their presence in these chambers, and avoided your control measures. You don't indicate when it was you treated the problem, but given how early in the year it currently is I assume it was last fall (??).

Carpenter bees of all species are pretty consistent with their life cycles. The adults emerge from winter hibernation, mate, and then they begin the excavation of the wood to create living quarters for their larvae. They may begin a brand new chamber in new wood or commonly will return to their previous home and continue the digging further into the wood. Once this is completed the female gathers pollen and nectar to create a ball of food, places it in the channel and lays an egg near it, and then seals off that chamber for that larva. She continues this to create around 8 or so chambers and then she is done and dies shortly after. The larvae develop and pupate during the late spring and summer, and usually in late summer the new adult bees emerge. You can see the delay in this time following the emergence of the over-wintering bees, particularly on a year when cold weather may have delayed their emergence and mating activity. These new adult bees then become the ones that will spend the next winter in hibernation. 

So, long story just to say that larvae probably are not currently in the wood, but perhaps adult bees are. Woodpeckers are well known for poking into infested wood to get to the helpless larvae, but would be less inclined to try for adult bees that might sting them. Either way it looks like these birds are causing damage, and woodpeckers may drill into wood for various reasons. During mating season males may pound on surfaces to make noise only as a territorial display. They may poke holes to create a cavity to nest in, and this is a common springtime ritual for woodpeckers, and I wonder if this is the actual reason the birds are now drilling holes in this house - nesting, not food. Your best bet is to install some physical barrier over the places they are drilling to prevent them from having access to that wood. This often is under the eaves, and bird netting from the ends of the rafters down onto the siding may accomplish this. Woodpeckers are, in general, protected birds that cannot be harmed, so exclusion is a much better route to take.