Have you been chased by a wasp lately? Or maybe you’ve opted to eat indoors to escape from wasps and bees messing with your picnic. Perhaps you’ve had to deal with a nest near or even in your home.
These insects seem to be everywhere lately — and they’ve stung some of us who’ve encountered them. So, what’s behind all that activity, and when might it come to an end?
To find out, Lake Effect’s Audrey Nowakowski spoke with P.J. Leish, an extension entomologist and the director of the Insect Diagnostic Lab at UW-Madison's Department of Entomology.
This conversation has been edited for length and clarity.
Audrey Nowakowski: Is it just me, or are wasps, hornets and yellowjackets way more active lately?
P.J. Leish: We are at the time of the year where we are seeing peak activity of bumblebees, paper wasps and yellowjackets. These insects have annual colonies. What that means is that the colonies naturally die out in the fall at some point, due to starvation and/or frost. But what happens is: they overwinter as a batch of new queens. They've mated; they're fertilized; they'll hunker down in a sheltered spot for the winter. In spring, all those queens come out of their hibernation, essentially. They get going, and they're trying to establish nests.
At first, that lone queen is doing all the work. Then, she raises a workforce and builds the colony up in size. Once she has a workforce, she's going to stay in the nest and lay eggs, while the workers go out and do the dangerous work of foraging for food and things like that. So, they start in spring with just that lone queen, she builds her workforce up, up, up, and it reaches peak size in late summer/early fall, which is where we're at. So, that's why we are seeing so much activity at the moment.
"If [wasps] get going earlier in the season, the colony has a longer stretch of time to build up, and that could result in colonies that could potentially be larger than what we've seen in the past — especially if that frost stays later out into the fall."UW-Madison Extension Entomologist P.J. Leish
AN: Has this behavior been impacted by climate change? We had kind of a mild winter, the summer's been very hot with sudden bursts of large rain at a time. There's no consistency. How is this impacting these insects that we're seeing everywhere right now?
PJL: To a certain extent, it's a little bit hard to tell. For some questions about what a population is doing, you have to look at long-term data sets. But, if climate change is leading to an earlier spring and a later fall, that could undoubtedly have impacts on things like yellowjackets. If they get going earlier in the season, the colony has a longer stretch of time to build up, and that could result in colonies that could potentially be larger than what we've seen in the past — especially if that frost stays later out into the fall.
Audrey Nowakowski: What kind of homes do wasps usually like to make? And with lots of people experiencing wasps in or near their home, why are they being drawn to other environments that maybe they typically wouldn't be in?
PJL: In terms of where they nest, it depends on the species. Here in Wisconsin, we have over a dozen species of yellowjackets alone. Some yellowjackets like to nest in the ground. They're not great diggers, but in spring, that queen may look for an abandoned chipmunk burrow, or a snake burrow, or something that's pre-existing that they can excavate it a bit over time. Others look for hollow logs or trees. It can also mean in and around human environments — in a wall or void of a home, in a soffit area or some other location like that, in a foundation of a home. Finally, there are other species that are aerial nesters. They make that papier-mâché type nest. That may be hanging from a tree branch, or it may be hanging off your soffit area on the side of your house.
This also goes back to why we're seeing so much activity this time of the year. That workforce, the colony, is at peak size. Back at the nest, they have all these larvae to feed, so those worker wasps are going out looking for food sources to bring back. And at the same time, those adult worker wasps need food too. So that's what's forcing them to show up in these areas. We have this combination of peak colony size, maximum workforce, lots of young in the nest. They need food and resources for it. So they are very actively out there looking for food. And that leads to more run-ins and interactions with humans.
"We have this combination of peak colony size, maximum workforce, lots of young in the nest. They need food and resources for it so they are very actively out there looking for food — and that leads to more run-ins and interactions with humans."
Audrey Nowakowski: Can homeowners, business owners or schools do anything to help mitigate this increased wasp activity?
PJL: There are traps available for things like yellowjackets. They are something that can help to a certain extent, but you have to look at the bigger picture. The traps are usually filled with some sort of sugary concoction, often a citrusy scent that can be pretty attractive to them. That can help, but it depends on the setting that it's in. If it's maybe a residential yard where you have fruit trees and there are fallen apples on the ground everywhere, there may be plenty of other things to draw wasps in. So, a trap might not do much in a situation like that.
For another example, if you think of maybe an outdoor dining establishment that has trash cans, recycling bins, caddies where you put your dishes and things like that building up, the trap might not do much, because there are so many other food sources around. So, traps can help to a certain extent, but they're not a magic bullet for these sort of situations either.
AN: When would you recommend calling professional backup, like an exterminator?
PJL: I would say it really depends on your particular situation and how comfortable you are dealing with things like this. But, for a bit of context, I will say that yellowjackets can be quite beneficial in many regards. They are predators of other insects. They can be scavengers and recyclers. They can be pollinators too. And so, I tell folks that if you have a wasp nest right outside your front door, you probably need to do something about that, so people aren't getting stung. But if that same nest were in the back corner of your yard, or it's 30 feet up in a tree and no one goes back there, it's perfectly fine to leave those. You don't need to eliminate wasps nests because of the benefits they provide. So, context is so important.
But, if you do have a situation and you're simply uncomfortable dealing with this, or if there are sting allergies, chat with a pest management professional. But, there are plenty of cases, though, where I feel these can be managed just with do-it-yourself methods. If you go to the hardware store, there's all sorts of aerosol wasp sprays. There are even some that dispense an expanding foam that can spray from 15, 20 feet away, so you don't have to get particularly close to that nest. If you have an exposed nest that's out in the open, that's relatively easy to spray. But, if the nest is in a wall void, a soffit area, or if it's down in the ground, those are much more challenging to deal with.
"Yellowjackets can be quite beneficial in many regards. They are predators of other insects. They can be scavengers and recyclers. They can be pollinators too."UW-Madison Extension Entomologist
AN: When do you anticipate that all this wasp, yellowjacket and hornet activity will die down?
PJL: That's kind of the million dollar question: when will this end? I can't give you a specific date. It's usually sometime in October, but it's really going to depend to a certain extent on the weather. As we get into fall, two things will be going on. First, these wasps start running out of food. As the insects and flowers start to senesce for the fall, they run out of food and start starving to death. Secondly, if we get an early frost, that'll probably end wasp season earlier. If it stays late and we don't get a frost into November, that could prolong wasp season a bit.
_
