Have Carpenter Bees, Will Burrow

Wednesday July 11, 2012


Mr Pest Control


I have a customer that has a new log home but is having trouble with carpenter bees. Is there any kind of preventive pest control for a log home?

Mr Pest Control


This can be difficult, and unfortunately chemical options are very limited and short lived. In the past there was pretty good success with the use of one of the microencapsulated pyrethroid products that could be applied generally over exterior surfaces during the period when the adult bees were actively seeking nesting sites. But, with the new pyrethroid labeling this kind of overall treatment on the exterior is no longer allowed, and spot applications only can be done, meaning you would have to pick and choose the places on that log home where you felt the bees were most likely to try to initiate their burrowing into the wood, and treat no more than a 2 square foot area around that point. This may still be somewhat helpful, as the bees may be most likely to look for some place where there is some kind of starting point for them, such as a knot hole, wide crack, or a seam between logs. 

Surface finishes such as paint, varnish, etc. will help to "discourage" carpenter bees, which would always prefer an unfinished surface, but this is no guarantee. Treatments with a borate product may be helpful but odds are they will not, as these bees are not eating the wood and borates are toxic only if ingested. There may be some slight ingestion as the bees nip off bits of wood and discard them, but I would not count on it, and some of the borate products are labeled only for use on unfinished wood products, so if this home's exterior does have some finish coating over the logs you would not be able to use those borate products. 

Bottom line may be that since you cannot prevent the bees from getting to the wood and cannot cover the logs with any impermeable barrier you may have to try the spot treatments with a labeled insecticide such as a microencapsulated material. There don't seem to be any non-pyrethroid replacements that offer the long residual and labeling for overall treatment. 

Mr. Pest Control

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Please note, Mr. Pest Control is answering questions supplied by PMP customers across North America. His answers are generated from industry and manufacturer-provided information. The answer may not be specific to the laws and regulations for your State, Province, Territory or Country. In addition, products mentioned may not be registered and or available in all areas. Always check with your local Univar office for specific information to your area. Always read and follow label directions.