Tuesday, October 7, 2008

Cool Weather Brings Insect Pests

Cooler weather is welcomed by most of us but what isn't welcomed is the accompanying increase in activity by some insects.

The "Polistes" or paper wasp colonies are beginning to wind down their activity, particularly in western NC. Some of the remaining workers (who will die in the next few weeks) along along with next year's crop of queens are bailing out of their summer nests. Neither pesticides nor the downturn in the housing market appears to deter these once and future queens from finding affordable housing.

We are getting calls from people who see the wasps outdoors hovering about the eaves, soffits, and porches, particularly on warm fall days. For whatever reason, the wasps seem to orient
to vertical objects so chimneys become an object of their attention. Same is true for cell phone towers, water towers and other such objects.

At some point, the wasps make their way indoors and things can get more exciting. You often see/hear the wasps moving about slowly and bouncing off windows, ceilings, light fixtures, etc.

Trips to the attic can be adventures as people often spot multitudes of the wasps buzzing about. Cold weather stops the activity, but quite likely on subsequent warm winter days you will find wasps flying about indoors or again spot them outside around the roof area.
Here are a few tips to remember:
First - seeing the wasps does not mean that there is a nest in a wall. More likely there is a nest outdoors nearby.
Second - since these are mostly queens looking for overwintering sites and not workers defending an active nest, they are not aggressive and so stinging incidents are rare.
Third - spraying indoors is an exercise in futility because there simply isn't a specific target area you can (or need to) treat.

When does it stop? Your guess is as good as mine. We're not into any real cold weather yet. As I said earlier, you can expect it even after periods of cold weather seems to have brought it to a halt, but when the outside air temperature (and sun heating walls of homes) is adequate for activity to occur you will see a them.


Best advice:
First - Keep a rolled-up newspaper handy. Yes, you can unload an entire can of "Raid" on the beast but then what do you do about its 'sisters' that are likely to show up?

Even that preferred weapon of choice for many homeowners - setting off foggers in every room - won't accomplish much either because any wasps that are not out in the open at that time will not be affected by the chemical mist.

For further information about paper wasps, check out:
http://insects.ncsu.edu/Urban/paperwasp.htm
http://insects.ncsu.edu/Other/note144/note144.html

Mike Waldvogel, NCSU Entomolgy

1 comment:

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