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Gypsy Egg Moths Prolific

The Gypsy Moth (Lymantria dispar dispar) was introduced to North America from France by E.L Trouvelot in 1869 who had hopes of breeding a silk-spinning caterpillar that was more resistant to disease than the domesticated silkworm.  Unfortunately, the caterpillars escaped into his backyard. About 10 years later, they began to appear in large swarms, and by the late 1880s they were causing severe defoliation in the area. Since then the Gypsy Moth has become one of the most destructive pests of hardwood trees in the eastern U.S. 

The adult female moths emerged from their pupae this summer.  With a life span of one week, the adults do not feed; they do, however, mate and lay eggs. Although the female moth has fully formed wings, she cannot fly.  She emits pheromones that attract males, mates and then lays a cluster of 75-1,000 eggs close to where she pupated.  She then covers them with buff-colored, hairlike setae from her abdomen, which serve as protection from predators and parasites.  The eggs overwinter and hatch in the spring.  The larvae have a voracious appetite and feed on more than 300 species of trees and shrubs. 

Gypsy Moth egg masses appear to be prolific this fall, perhaps because there has been no significant wet weather to fuel the fungus (Entomophaga maimaiga) that feeds on the Gypsy Moth. While there are other natural controls for Gypsy Moths (birds, squirrels, mice, etc.) they don’t prevent infestations.  If you wish to rid your woodlot of these caterpillars, you can remove the egg masses and pour boiling water over them.  Scraping the eggs onto the ground is less effective as they can survive temperatures of 20°- 30°F. degrees below zero.

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6 responses

  1. Here in Southern Ontario, Canada I have never seen so many Gypsy Moth egg masses. I spent a lot of time in August looking up and killing the female moths, as they don’t fly and once spotted I could dispatch them. After they finished breeding I also spent a lot time educating people on what to look for and how to dispense with these moths. I can see that once eggs have hatched next year more time will be spent putting up barriers on trees to entangle the caterpillars crawling up tree trunks. Next year promises to be a very destructive year for the trees of our area due to this introduced species. Now, I await the Lantern Moth.

    November 20, 2020 at 9:20 am

  2. leaf04

    We used to burn them off with judicious use of a blowtorch!

    Thanks for the heads-up; I’ll keep an eye on my trees.


    On Fri, Nov 20, 2020 at 8:25 AM Naturally Curious with Mary Holland wrote:

    > Mary Holland posted: ” The Gypsy Moth (Lymantria dispar dispar) was > introduced to North America from France by E.L Trouvelot in 1869 who had > hopes of breeding a silk-spinning caterpillar that was more resistant to > disease than the domesticated silkworm. Unfortunately, the” >

    November 20, 2020 at 9:43 am

  3. Alice

    I can remember 1980 as a horribly prolific year w/ gigantic caterpillars…. kept picking them off the trees. Last 2 or 3 years I’ve very infrequently seen a caterpillar or moth…same goes for the winter-moths/canker caterpillars…seem to have disappeared because of the introduction of a voracious wasp.

    November 20, 2020 at 9:54 am

    • Alice

      …and there are those (neighbors) who refused to listen to what I was telling them about the multitudes of egg masses on their trees.

      November 20, 2020 at 11:17 am

  4. Amy

    Ugh. 2020 strikes again.

    November 20, 2020 at 9:57 am

  5. Thanks for the heads up, Mary. They are such a destructive species.

    November 20, 2020 at 5:06 pm

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