Good Growing

Ken Johnson: 00:04

Welcome to the GetGoing podcast. I am Ken Johnson, horticulture educator with University of Illinois Extension, coming to you today from Jacksonville, Illinois with a Gardenbite. And on this week's garden bite, I'm gonna talk a little bit about wasps, good bugs that get a bad name. So typically, when we mention wasps to somebody, usually, we're going to get a negative reaction.

Ken Johnson: 00:27

We often see wasps as scary, angry, aggressive insects. They're dangerous and are likely to sting, when provoked. While some wasps can be aggressive at times, and and a lot of them will pack a powerful, painful sting, they're actually good insects to have around. In a lot of cases, they are the unsung heroes in a lot of our landscapes. So why do wasps, get a bad name?

Ken Johnson: 00:51

Like many other things, one or a handful of individuals kinda ruins everything for everyone else, and wasps are gonna be no exceptions to this. So there are around one there are over a 100,000 described species of wasps worldwide. Of those, about 33,000 are considered stinging or the aculeate wasps. And about 1,000 of those are going to be social. So things like yellow jackets, ball faced hornets, paper wasps, and so on.

Ken Johnson: 01:19

And these are the wasps, these social wasps are typically the ones that are gonna give the entire group bad name. They're the ones that we most commonly interact with and are most frequently stung by. So while they're out foraging, social wasps aren't particularly aggressive, but that all kind of changes when when nests are involved. So social wasps, and particularly yellow jackets, kinda notorious for aggressively defending their nests, which, again, can result in painful stings, for those of us that may get too close or accidentally disturb those nests if we don't know they're there. But not just wasps will do this.

Ken Johnson: 01:55

When we think about social bees like honeybees, bumblebees, things like ants, they will also defend their nests from perceived threats. So why do wasps get a worse name than these other stinging insects? Is it because their stings are, on average, more painful? The stings of wasps are more painful on average than than those of bees or ants. Or is it because we don't recognize or maybe we're unaware of the benefits that wasps provide like we do, for example, for bees.

Ken Johnson: 02:25

Bees are widely accepted as as very important pollinators, and we need them. But wasps also provide many different benefits to us as humans. So some of those different benefits. Pollinators. So while bees get most of the attention when it comes to pollinating insects, wasps will also act as pollinators.

Ken Johnson: 02:44

While the the larvae of most wasps are going to be carnivores, gull wasps would be an exception to this, the adults are gonna feed on sugars, which is why we commonly see them on sugary drinks, especially in the fall. But for the most part, they're often getting this in the form of of nectar. So while feeding on nectar, wasps may also pollinate flowers. And in some cases, they can be as efficient as pollinating as bees, or can even take the place of bees. So there's some research done in Wisconsin, and I will include a link to the the paper in the show notes here, where they looked at world milkweed, and they excluded bumblebees from an area with, world milkweed, and they found that, paper wasps were able to come in and replace, bumblebees and and were just as effective at pollinating, the world milkweed as bumblebees were.

Ken Johnson: 03:34

So they can be important pollinators for our plants. Next, they can be important predators. So wasps are gonna be vital for controlling insect populations in our landscapes. Again, our social wasps will capture a wide variety of insects. They're kind of generalist predators, so they can catch it.

Ken Johnson: 03:50

They're gonna do that. So this can be things like flies, caterpillars, beetles, they'll catch them, they'll chew them up, they'll kind of masticate them, and then they will feed them to their larvae. Solitary wasps, on the other hand, tend to be a little more focused on what they're feeding their young. They often attack one one type or one group of insects. So example, great golden digger wasps, great black wasps, will paralyze catidids, grasshoppers, crickets, those related insects.

Ken Johnson: 04:14

They'll bring them back to the burrows, as food for their for their larvae. Other things like the blue winged wasps will dig into the ground, and they will paralyze and lay eggs on grubs of scarab beetles, so like June beetles, Japanese beetles, and they can be important for helping to control the populations of those insects. Parastoid wasps are also incredibly important when it comes to controlling insect populations. So these are not sting what we would consider stinging wasps. Most parasitoid wasps are gonna be very small.

Ken Johnson: 04:42

Most of us would probably confuse them for a gnat. And a lot of times, they may only attack one type of insect, like caterpillars, or in some cases, they may be specific to the species. They only attack one species of insects. But there again, they're gonna attack all kinds of different insects. Pretty much any insect is gonna have some parasitoid wasp that's going to attack it.

Ken Johnson: 05:02

But for for us as as gardeners, for example, aphids, whiteflies, mealybugs, caterpillars, insect eggs, they all those are all readily parasitized by various types of wasps. Now, so what they'll do, they will lay an egg in or on an insect, and then that egg will hatch, the larvae will consume their host. In the case of aphids, those eggs are laid on the inside of the aphid. The larvae eats the inside of the aphid. It'll pupate, and the adult wasps will emerge from that aphid.

Ken Johnson: 05:29

They'll go out and lay eggs in new hosts. So a lot of times, for some of our smaller insect pests, like aphids, if we just leave those alone long enough, our our parasitoid wasps and other beneficial insects will eventually find those and clean up those populations for us without us really having to do much to them. Wasps also act as food for other organisms, so not only are they eating stuff, stuff is going to be eating them. So a lot of different birds, crows, orioles, bluebirds, sparrows, chickadees may eat wasps as part of their diets. There are some other birds like the summer tanager, which specialize on bees and wasps, but it makes up majority of their diet.

Ken Johnson: 06:06

Even some mammals, bears, which may or may not be all that important for Illinois, but skunks, sometimes raccoons, will dig up yellow jack in this and feed on the larvae occasionally. Other insects will also eat wasps as well. So praying mantids, dragonflies, robber flies will also feed on wasps, as well as other wasps will consume wasps as well. Wasps can also be important in seed dispersal. So some plants are gonna rely on insects to disperse their seeds.

Ken Johnson: 06:32

Usually, this is ants. When we talk about the elaiosome, those fleshy structures, they're full of fats on those seeds. Typically, it's ants moving those seeds around. A lot of our spring ephemerals will do this. But in North and South Carolina, they found that yellow jackets play an important role in the dispersal of Trillium seeds.

Ken Johnson: 06:48

So not only ants are doing this, in some cases wasps will also distribute these seeds. In the case of wasps, they're probably distributing these seeds much farther than ants would because they're flying. So one common issue we have with wasps is in the fall. A lot of times wasps, particularly yellow jackets, unwelcome guests at outdoor activities, But, in reality, all they're doing is looking for something to eat. As fall approaches and we progress through the fall, a lot of flowers stop blooming.

Ken Johnson: 07:18

We think about our typical landscape. There's not a whole lot blooming during late summer into the fall months. And this is gonna reduce the amount of food that's available for yellow jackets and and other social wasps, and and really other insects that are relying on pollen and nectar. In the case of yellow jackets, you know, in addition to this lack of food, these nests are gonna contain thousands of workers. And because of this lack of food, a large number of wasps, they begin searching far and wide for food sources, and they're gonna be attracted to sweet food items, carbonated beverages, pop soda, whatever you wanna call it, juices, candy, fruits, things of that nature.

Ken Johnson: 07:54

So if we wanna avoid, issues with these wasps, we wanna place beverages on cups where you when you're outdoors, you can see what you're drinking. A lot of times if it's in a can, they can get in there and you may not see them. Go in there. If a yellow jacket, you know, decides to to check out your food or lands on you, blow it or brush it away rather than swatting at it, which many times will result in you getting stung if you're swatting at them. Just kinda gently move them away.

Ken Johnson: 08:19

Another thing we can do is provide those fall blooming plants, goldenrods, asters, and this is gonna provide them with a we could say an alternative food source to the food from the the picnic or whatever you're you're consuming outdoors. If you do run into a yellow jacket or a bald face hornet nest, things like that, again, those can pose a risk. If those are located away from high traffic areas, areas where people aren't nearly necessarily going all that often. One good option is just to wait and do nothing. The these social wasps that we have in Illinois, they are gonna die out once temperature cold temperatures arrive.

Ken Johnson: 08:56

We get a couple frosts. Those nests will dry off or die off, and they don't reuse those nests. So it's it's kind of a one and done thing. So once we get a frog couple frosts, those nests will die. They're not gonna be there again next year.

Ken Johnson: 09:09

However, if they do pose a threat to people that are in a high traffic area, front door, by a sidewalk, area where where kids are playing, we do probably need to do something about that. So when it comes to managing, these nests, first thing is to remember, if accessing the nest is difficult or if you're uncomfortable treating yourself, you wanna contact a professional pest control company to do this, because we are dealing with stinging insects, and this this can be kinda dangerous to do. If you want if you're gonna if you're comfortable, and you wanna do it yourself, the best time to treat these nests is going to be at dawn or dusk when they are gonna be less active. All the wasps have returned to the nests as well. And we're doing this we're doing this at night.

Ken Johnson: 09:51

It's important to know that the wasps will fly at light sources. So if you're gonna be doing this, if you're using a flashlight, cover it in red cellophane, use a red light. They cannot see red very well, so you're gonna be they're not gonna come out and attack that light, where if you have a white light, they'll come after it. Again, you wanna wear protective clothing, long pants, long sleeves, gloves. Good idea to duct tape those to make sure they can't crawl up them.

Ken Johnson: 10:14

If you can get something to protect your head, beekeeping, veil, something like that. Try to cover yourself up as much as possible. In the case of, like, in ground yellow jacket colonies, we wanna apply an insecticide to the nest, whether that be a liquid or using them on those aerosols or a dust. We're gonna place that in the entrance down into the hole in the ground. And a lot times we were gonna put a shovel full of treated soil over that exit hole.

Ken Johnson: 10:38

So if they try to bury out of there, they're consuming that insecticide, and killing off the individuals in that nest. Now, same thing with an aerial nest. We wanna use aerosol spray. Some of those can spray 20 plus feet, and again, we're aiming that towards the entrance of the nest. If the nest is inside of a building, again, typically, we're gonna be using an insectile dust for this, putting that on the wall openings where the yellow jackets enter.

Ken Johnson: 11:03

But in this case, we don't wanna seal the entrance to that colony if it's in a wall. Doing so, that may cause them to chew through the walls into other parts of a home or or something like that. So, again, if you're not comfortable doing this, contact a a professional to do this. But again, overall, our our wasps are going to be beneficial in our landscapes. Again, you know, obviously, if they're they're posing a threat, we wanna do something about them.

Ken Johnson: 11:29

But if they're out of the way, we can leave them be, and they'll be gone come cold weather, and they're not gonna reuse those nests. So while wasps can be be annoying, and it can be painful at times, their their benefits are gonna far outweigh the drawbacks. But from the pollination services they're providing, the pest management, insect management, they're providing and they're helping to disperse seeds, their food sources for other organisms as well. Well, that's all I've got for you for this week's Garden Bite. Hopefully, you have a a little bit better appreciation, for wasps, and maybe we can get away from the the only good wasp is a dead wasp approach that many people have.

Ken Johnson: 12:07

Good Growing podcast is a production of University of Illinois Extension. Listeners, thank you for doing what you do best and that is listening. Or if you're watching us on YouTube watching. And as always, keep on growing.