What You Need to Know About Gypsy Moths

The DNR says the gypsy moth infestation that’s been plaguing our service area for some time is back again this year. This little guy can destroy a neighborhood full of trees in just a few short days.

And while it’s a little late to remove egg masses if you didn’t get a chance to last month, it is the right time to call a certified arborist about applying some pesticide.

But gypsy moths are a year round problem. If you have them on your property you’ll almost have to manage them all year round.
First, know the signs of an infestation. This handy guide will help you find these insects at any part of their life cycle.

Management strategies correspond with the life cycles of the moth.

This is the time of year where the caterpillars are hatching. You might see large, ugly egg masses on your trees, complete with caterpillars crawling out.

That’s what makes May and June ideal for applying pesticides. Note, the DNR really prefers you to use a certified arborist for this job.

By late June to mid-July the caterpillars will be mature. They’ll be going into their cocoons. They’ll emerge as moths by August.

In June, you can start placing collection bags on your trees. You’ll use wide burlap to make a sort of collar around the tree at chest height. Fasten twine at the middle and fold the top down. You do this to make it easier to kill caterpillars, who will choose this spot to hide in. Every day you can just scrape them off into a bucket of soapy water. You can do this all summer as you find them. It’s not a fun job, but it will save your trees.

They start mating in July, almost as soon as they are out of their cocoons. Applying female moth pheremones to all of your trees means the male moths will have a hard time locating the females. This means less eggs later. You can also use gypsy moth traps.
It’s really only effective if your gypsy moth population is very low, though, so if you want to save the money you can skip it.

You’ll start finding eggs by mid-October. Winter won’t kill them! You’ll have to destroy them yourself, which you can do all the way into April. You can do this either with a gypsy moth horticultural oil from your local garden store, or by just gently scraping the egg masses into a can of soapy water. They’ll have to sit in there for two days before they’ll be safely dead. Then you can throw them away.

Most people find the sprays easier. Using them reduces the likelihood that you’ll damage the tree yourself trying to dislodge the egg masses.

Remember, we’re not tree specialists. We’re fence contractors who just happen to be passionate about keeping trees healthy. After all, we need trees if we’re going to keep building wooden fences! If you need help with your trees, contacting an arborist is usually the better part of valor.

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