We definitely have an infestation of carpenter bees in an old barn, since we have never treated for them before. When the bees are not active, from late evening to early morning, where do they go? Do they stay nearby? Do they stay together? Can I spray them at this time?
As explained in our CARPENTER BEE CONTROL ARTICLE, females are usually drilling out new holes or utilizing old ones from the previous year. If you are seeing bee activity around your barn, there is most likely some old nests somewhere you should be able to find or new ones being drilled. Just do a thorough inspection and look for 1/2″ holes. Old holes will be clean and throughout the day bees will be entering and leaving. New nests must be drilled by females and this drilling will produce a lot of sawdust so look around for any accumulating around the structure. This would be sure sign of new nests.
As the sun sets both females and males will return to their existing holes and it’s at this time when dusting with DRIONE is most effective. If you treat in the evening, let the holes sit open over night and then seal them up the following day with CORKS. If you cannot locate any holes, treat all exposed wood with CYPERMETHRIN and they’ll stay away. The Cypermethrin will both chase foraging bees away and stop new nests from being drilled but it won’t take care of old nests; for that you’ll need to dust with the Drione.
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