Hi, I want to spray bifenthrin on my soffits and windows on one side of my house to target wasps (bees do not fly there). However, there is also a la...
Knowledgebase
Residual Bifenthrin, Wasps, Bees #850464
Asked September 19, 2023, 12:44 AM EDT
Hi, I want to spray bifenthrin on my soffits and windows on one side of my house to target wasps (bees do not fly there). However, there is also a large host lilac shrub on an adjacent side of the house where a lot of bees and wasps feed together. I couldn’t find any information on if residual bifenthrin from the wasps’ bodies would impact the bees on nearby flowers. Or, would the bifenthrin kill the wasps within 15 minutes before they are able to fly to the lilac bush? I know bifenthrin is not an instant knockdown. I'd like to resort to spraying bifenthrin since I cannot find the wasp nest, but observe them flying into the soffits and gathering around particular high windows. I have been stung a few times by them. I've also tried traps to attract only the wasps and not the bees, to no avail. Thank you!
Washington CountyMinnesota
Expert Response
Here's a useful fact sheet about bifenthrin from the National Pesticide Information Center As you note, the chemical will affect bees and wasps equally.
It's clear from your description that you can't see the wasp nest(s). However, if you can identify an opening where the wasps are entering the soffit or window casing, it's recommended that you apply a dust pesticide such as Bonide’s Spider & Ground Bee Killer to those openings. This targeted application will help minimize the risk of bees coming into contact with the pesticide.
Ellen Tveit Replied September 20, 2023, 5:58 AM EDT
Thanks, my main concern is: Will pesticide residue on the bodies and legs of exposed Wasps (from liquid bifenthrin, powder bifenthrin, or any other pesticide for that matter) be able to be transplanted to flowers, and therefore have an impact on Bees? My thought is that (1) The exposed Wasp is already in a toxic state, where they might not be able to fly around and feed on the same flowers and lilac bushes as they normally do with the Bees (bifenthrin is not an instanct knockdown). And (2) Even if they were, the residual pesticide from the Wasps bodies and legs would be low enough to not impact Bees. After hours of research, I haven't been able to find any information on residual pesticide from other insects (like Wasps) indirectly affecting Bees via pollination / feeding on the same flower. I appreciate your time and response! - James
I suggest you contact Marissa Schuh, an entomologist with University of Minnesota Extension. She's much more likely to be able to access research-based information to answer your question. Her email is <personal data hidden>.
Ellen Tveit Replied November 03, 2023, 2:21 AM EDT
