Gypsy Moth

Gypsy Moth

Part of Ep. 903 Fall is for Planting and Picking

Join Andrea Diss, the program coordinator for the gypsy moth program at the Department of Natural Resources (DNR), for advice on combating gypsy moths. The moths are a problem because they cause significant defoliation of Wisconsin trees. Diss explains how homeowners can kill eggs, disrupt larvae habitats with barrier bands and capture adults with collection bands.

Premiere date: Oct 03, 2001

TRANSCRIPT+
Wisc Gardener Transcript: 

Shelley:
These little brown lumps are responsible for the defoliation of trees in many parts of Wisconsin. These are the egg masses of gypsy moth. And we're going to talk about what to do if you find them in your yard. I'm with Andrea Diss, and Andrea is the program coordinator for the gypsy moth program for the Department of Natural Resources. Andrea, let's start out with a little history about gypsy moth. Where did it come from?

Andrea:
Well, it's a foreign pest, and its only recently arrived in Wisconsin and started getting to be a problem. The reason why gypsy moth can be such a problem for us is that it's naturally a species that can increase to very high densities over a short period of time. Most of the time, say ten years, we won't have problems with the gypsy moth, but--

Shelley:
We will have population explosions.

Andrea:
Periodically, that's right.

Shelley:
And it's the larvae of these egg masses is what the problem is, they eat leaves.

Andrea:
That's right. The gypsy moth defoliation peaks in late June when the larvae are about the size of my finger, and the devastation can be really quite appalling. Entire trees can be stripped out, even entire forests.

Shelley:
Sometimes they can die because of the stress too, right?

Andrea:
Yes, and this can be a particular problem for our yard and street trees, because they're often under a little bit of stress to begin with.

Shelley:
Okay. Now, there's also a stressful problem for people.

Andrea:
Yeah, gypsy moths can be a problem for us as well. Daily, they come down out of the trees to hive when they're a little bit larger, say in June. And this puts us in contact with them. The gypsy moth is covered with these defensive hairs, which are shaped like miniaturized porcupine quills. And it's very irritating for our skin, just that, but they're also tipped with a chemical that can raise a rash in many people. So people who come in contact with them can get rashes. The other problem is that these hairs can get into the air when the gypsy moth sheds its skin on a weekly basis, and this can really exacerbate asthma.

Shelley:
Wow, okay. So what can we do about it?

Andrea:
Well there's a lot of things we can do about gypsy moths in our yards.

Shelley:
Let's start with the egg masses then.

Andrea:
Right. The egg masses are present between August when they're laid by the adult and May when they hatch out in the larvae. And so that gives you a long period of time when you can attack this stage.

Shelley:
What trees are we likely to see these on? All trees?

Andrea:
Well, actually you can find egg masses on just about anything. Anything that could provide some protection. You'll often find them on oaks because the gypsy moth does very very well on oaks and they really prefer those species. But you can also find them on the sides of buildings, under trucks, on wood piles, all over the place.

Shelley:
Okay, do I start attacking them in the fall? Or should I wait until spring to do that?

Andrea:
Actually, I would recommend that you start dealing with the gypsy moth egg masses when the leaves have dropped and we've gotten a freezing frost. Because we do have some helpers out there in the natural world. There's a parasitic wasp that attacks the egg masses when the weather's still warm in early fall.

Shelley:
Okay, so we don't want to hurt those.

Andrea:
That's right. So start when the leaves are off the trees, you can see them better then. There's a couple of things you can do to kill the eggs in the egg mass, and this is really the stage to attack because every egg mass has 600 to 1000 eggs in it.

Shelley:
Let's get them then!

Andrea:
You can use a spritz of Golden Natural oil, or you can scrape off the egg masses into a cup and either microwave them or cover them with a mixture of soapy water or you can use a mixture of oil and water.

Shelley:
Okay, we're smothering it.

Andrea:
Right.

Shelley:
Now we're still going to have others higher up in the tree, can we do something later in the season too?

Andrea:
Yes, there are some other things you can do against the larvae. Now the eggs hatch out in early May, and at that point, the larvae tend to do a little bit of dispersing and falling out of the trees. So, if you can prevent them from getting back up the tree, then you've dealt with those. What we do is put a barrier band up. It's duct tape and then you put a thin layer of a sticky material, like tangle foot. And that prevents the caterpillars from crawling back up into the trees.

Shelley:
They get stuck.

Andrea:
Exactly. Then, later on in the season, when the caterpillars are a bit bigger and they've started their daily migrations up and down the tree, you take the barrier band off, because it's not sticky enough to help with the big larvae. And instead, put a collecting band up. And that's a burlap skirt. And the caterpillars find this irresistible and they'll collect underneath in large numbers. And what you can do is go out after work or after school in late afternoon and just flick them into a cup of soapy water, turn yourself into a super-predator and make a dent in the late larvae population.

Shelley:
So, we can do things to help.

Andrea:
That's right, you can.

Shelley:
Thank you, Andrea. For more information about gypsy moth, contact your local county Extension Agent. Or, if you think you have a problem, contact your local county government and ask for information on the gypsy moth suppression program.

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