PJ Liesch, UW-Extension entomologist
Department of Entomology
UW-Madison College of Agricultural and Life Science
Total time – 3:03
0:14 – End of mosquito season
0:29 – Appearance of floodwater mosquitoes at the end of August
1:17 – How long can eggs last
1:31 – What will make the mosquitoes leave
2:20 – Eliminate standing water
2:51 – Lead out
Lorre Kolb: The end of season for mosquitoes or is it? We’re visiting today with PJ Liesch, Extension entomologist, Insect Diagnostic Lab, University of Wisconsin-Madison/Extension in the College of Agricultural and Life Sciences and I’m Lorre Kolb. PJ, are the mosquitoes ever going away for the season?
PJ Liesch: Well, the good news is they will be and I think the cooler temperatures we’ve been having lately are already starting to bring about that end of mosquito season, but it was a really unusual end to the summer for us.
Lorre Kolb: We seemed to have a new batch of mosquitoes right toward the end of August beginning of September, what happened there?
PJ Liesch: It really boils down to the rainfall and if you think about the rainfall events, we had those storms we had late August and early September, much of the state got dumped on with several inches of rain and some areas had massive flooding issues and there was flooding all over the place. That really set the stage for a certain type of mosquito we call our floodwater mosquito that really are opportunistic creatures and they take advantage of these temporary pools of water out in the woods and it turns out they have laid eggs in the past. It might have been last year, it might have been a few years ago, the eggs simply sit and wait for the rains to come, once they showed up like they did, it’s about a week or two later you get a big explosion of mosquitoes and that’s exactly what we saw in Wisconsin in the month of September.
Lorre Kolb: How long can the eggs last?
PJ Liesch: They can last quite a while. Sometimes eggs laid this year might hatch next year, if we had heavy spring rains, if it’s a relatively dry period they might end up sitting for a couple years, just biding their time waiting for the rains to come.
Lorre Kolb: What will make the mosquitoes leave?
PJ Liesch: Ultimately it’s going to be the cooler temperatures. The mosquitoes we’re see that are really abundant at the moment don’t survive the winter as the adults. They survive the winter as the egg stage, so when we get a couple of good cold hard frosts, that’s going to put an end to those. In the meantime, with the temperatures cooling down, once we get into the 50s and low 60s they become kind of lethargic and you get down under 50 they’re just too slow to fly let alone pursue you for bloodmeal. So the cooler temperatures we’re seeing will help. I like to tell folks if it’s good flannel weather outside, the mosquitoes probably aren’t going to be very active. So simply waiting it out, waiting for cooler temperatures, they’ll disappear on their own. If you are out, if it’s a pleasant warm fall day, you may still need some repellent, so DEET, picaridin and other EPA approved repellents may still be helpful in those situations.
Lorre Kolb: If people have standing water on their property, what should they do?
PJ Liesch: Well, it’s always a good idea to try and minimize or reduce or eliminate, if possible, standing water on your property, especially from manmade items, kid’s buckets, the sandbox, or tires, things like that. If we have standing water around there may be some mosquito species that can take advantage of it. In this case with the floodwater mosquitoes we’ve been seeing, they can fly in from several miles down the road and those situations we can’t do a whole lot about eliminating those mosquito species.
Lorre Kolb: We’ve been visiting today with PJ Liesch, Extension entomologist, Insect Diagnostic Lab, University of Wisconsin-Madison/Extension in the College of Agricultural and Life Sciences and I’m Lorre Kolb.