Eastern Tent Caterpillars

Eastern Tent Caterpillars

Part of Ep. 204 Container and Shade Gardening

Damage wrought by the Eastern Tent Caterpillar is only cosmetic. Entomologist Phil Pellitteri explains natural methods for controlling the insect.

Premiere date: May 31, 1994

TRANSCRIPT+
Wisc Gardener Transcript: 

Shelley:
You're looking at the tent of the Eastern Tent Caterpillar. If you haven't seen these yet, you're likely to see them soon along roadsides and in thickets. I'm with University of Wisconsin- Extension entomologist Phil Pellitteri. Phil, these are awful looking. What plants are they actually attacking?

Phil:
Eastern Tent Caterpillar only feeds on flowering fruit trees, so we see them on flowering crabs, apple trees, wild cherry, plum, that type of plant

Shelley:
What do I do to get rid of it?

Phil:
It's really pretty simple. We know the eggs hatch about the time the tree starts to leaf out. So, what you look for are these small tents. You can prune them out, take a piece of newspaper and crush them, use insecticidal soaps, bacterial products--you can even use most garden insecticides and get pretty good control.

Shelley:
And that's when they're small at this stage. I've seen some tents that are a lot bigger. What about them?

Phil:
If you let them go, what you're going to find is that they get very large and you notice that all the leaves are gone. One of the reasons is these little caterpillars are eating two to three times their body weight in food a day. At this point, they're just about done feeding. They'll crawl off the tree. They'll spin their cocoons and really, the damage has been done.

Shelley:
Now, have they killed this tree?

Phil:
No, that's a mistake most people make. If we come back in a couple of weeks, the tree will leaf out again. It has cost the tree some energy. If it was an apple tree, it would affect fruit production. But, relatively speaking, it's more of a cosmetic type of damage.

Shelley:
Well, I've seen people go out and torch their trees when it's like that. That's not a good idea, then.

Phil:
It's a real mistake. What you find is with fire will do more damage to the trees than the worms ever could. And so, we really don't recommend going after it. Plus, at times you have some potential danger if the fire gets away.

Shelley:
As you said, though, it is a cosmetic problem. If I don't want to see these, can I prevent them from ever happening?

Phil:
Really, a good approach is that the insect lays its eggs in the end of June and what we have here is an egg nest. And, these egg nests can be found and you can either go out and prune then. You can crush them with your hand. Or, when you get into the spring of the year before the tree leafs out, you can use a product called dormant oil and spread it on the tree. Those oils will suffocate the egg masses and they work very well.

Shelley:
Well, these look a lot easier to crush than this entire tent, too.

Phil:
Yeah, people, I think, feel a little more comfortable dealing with the egg nest than they do the worms.

Shelley:
Well now, I've heard that people confuse these with gypsy moth. What's the difference?

Phil:
Gypsy moth doesn't make a tent. Gypsy moth attacks far greater numbers of trees. But if you look at the worms, the tent caterpillar has a nice, bright white line down its back. Gypsy moth has a pair of both red and blue dots down its back that are very distinctive.

Shelley:
So, then this is just the Eastern Tent Caterpillar and we don't need to worry.

Phil:
No, not a problem at all.

Shelley:
Okay, thanks, Phil. So if you see these tents in your back yard, don't panic.

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