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Cool Weather – Uncool Pests (Nov 13, 2017)
By Dr. Michael Waldvogel
 
Colder temperatures are often accompanied by a surge in what we call “occasional invaders” and that “occasion” is now.
 
We have had a few reports of kudzu bugs making their way onto and into buildings. At this time of year, the bugs are heading out of soybeans and kudzu as they such for some place to pass the winter. In recent years, kudzu bug invasions had seem to taper off as a naturally occurring fungus, Beauveria bassiana, reduced populations in soybeans and other crops. However, numbers seem to be on the rise again.
 
Similarly, we’ve had a few calls about the multicolored Asian lady beetle, Harmonia axyridis, deciding its time to head indoors.(likely wanting to stake their claim to some prime areas before the kudzu bugs get there!). Most of the contacts I’ve had about the beetles have been from the western part of the state.
 
Kudzu bugs on house
 
Multi-colored Asian lady beetles – Michigan State University Diagnostic Services
 
Both of these insects are “invasive species” (meaning they’re not native to here or actually to the U.S.). The kudzu bug was a more recent introduction (down in Georgia originally in the counties surrounding Atlanta). While one is a plant pest (the kudzu bug) and the other dines on plant pests (the lady beetle), they both have the same behavior of hunting for protected areas in which to pass the winter and what better place to do that (from their perspective) than our homes and businesses. Spraying the exterior of buildings is unlikely to stem the invasion for a variety of reasons including most notably, the simple fact that this invasive behavior occurs over weeks and the pesticides have trouble keeping the numbers down. Also, treating every critical exterior area of a building is difficult, if not impossible, and possibly hazardous as well. Spraying indoors is equally unproductive because you can’t treat every nook and cranny through which the insects may enter and even then those surface residues can pose a hazard to people (particularly children touching those treated surfaces) and often pets as well. That’s why we continue to offer the same advice which is often not received warmly that the best control is to suck up the insects in a vacuum cleaner and dispatch them immediately.
 
Polistes Wasps
 
We’re also seeing the end of another year of Polistes (aka, “paper”) wasp activity. These are the wasps that build nests in protected areas like attached to your soffit or/under your covered porch, etc.  At this point in the year, the workers in the colony are dying off and what remains are next year’s group of queens who also leave the happy confines of this nest and seek out places in which to pass the winter. As with the kudzu bugs and lady beetles, they find their way into your home. On warm fall days, you’ll see them flying about particularly around the fasica and soffits looking for an entry point. They seem to have a fondness for vertical objects and so you’ll also see them flying around chimneys. Not to be outdone by a mere bug or beetle, paper wasps cannot be easily stop with pesticides at this point. You can kill the ones congregating on a nest (as seen in the picture). However, there are plenty of nests in other areas around your property.
 
Polistes wasp on ceiling 
 
Once they’d enter your home, the excitement rises as you’ll be sitting watching TV when one of the wasps will buzz by your face or be smacking into the sides of your lampshade or will keep your cat entertained as the wasp crawls across the wall or ceiling (and your cat is plotting how to reach it!).
 
Fortunately, the wasps are not in “defensive mode”, i.e., they’re not defending a nest and so they are not inclined to sting (they’re just trying to figure out how they got onto your ceiling). They can be easily dispatched with a rolled-up newspaper or your shoe (preferably not smearing wasp guts across your wall or ceiling in the process!). Most stings are accidental, such as you sit down or lie down on top of one, or (as I have done) when you start to lace up your running shoes in the morning and discover the hard way that one errant wasp had taken up residence in your shoe overnight. And yes, I can attest that it: a) does hurt, and b) they can sting many times! I can also tell you that I’ve killed more than two dozen in a single day (there is no “bag limit” on how many you can kill during the season).
 
This activity should draw to a close in a few weeks. I can’t tell you when it will stop. If I could predict things like that, I wouldn’t be writing this article, I’d be out picking lottery ticket numbers.
 

 
 
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