Discover The Moth That Can Kill 20% of North American Trees (European Gypsy Moth)

Written by Kirstin Harrington
Published: April 26, 2023
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The Spongy Moth previously known as the European Gypsy Moth is a pest unlike any other. They are an invasive species known for destroying several types of trees, damaging homes, and more. 

The ravenous larvae of these moths totally defoliate trees if left unaddressed frequently resulting in tree mortality. In the Northeast and Upper Midwest, the moth’s devastation has resulted in the loss of large tracts of forest and numerous trees in residential landscapes.

The caterpillars’ feces and extensive infestation destroy lawns, preferred seating areas, and outdoor recreation areas. Whether you’re dealing with a moth problem on your property or just looking to learn something new, keep reading to find out much more about the Spongy Moth.

What Causes Spongy Moths?

The widespread pest known as the “spongy moth” has a varied diet. If your land contains the following plants, it will serve as an inviting habitat for multitudes of sponge moth larvae to deposit their eggs and subsequently feast on plant leaves. Consider the spongy moth when choosing ornamental plants that are disease- and insect-resistant. The following trees attract spongy moths: 

  • Oak
  • Willow
  • Apple
  • Crabapple
  • White birch
  • Witch hazel
  • Mountain ash
  • Basswood
  • Linden
  • Pine
  • Douglas Fir
  • Spruce

Signs of Spongy  Moths

Sponge moth larvae eat hundreds of different kinds of plants, but trees are the ones that suffer the most from their destruction. Trees either totally shed their last leaves or appear to have fallen, which provides a dramatic effect. 

Tree limbs wither and tree tops thin from these pests. Even once healthy trees may die away due to disease and pest infestations that weaken them. Larvae that have just emerged from the egg are hairy and black, and they feed by gnawing tiny holes in leaves. 

Older larvae consume leaves in their entirety. The larvae have a dark, fuzzy body with red and blue patches on the back. 

A further sign of spongy moths is the development of squishy egg clusters in the latter part of July on tree trunks and limbs. They also can be found in forest detritus close to defoliated trees. These egg masses are encased in brown or buff-colored hairs from the female’s belly. 

Trees and bushes are entirely defoliated across significant regions amid extreme outbreaks. The damage results in a severe loss of growth despite trees’ capacity to generate a fresh crop of leaves over the height of summer.  Plants and bushes in the understorey may also be impacted by these pests. 

Spongy Moth Life Cycle

The spongy moth, sometimes known as the gypsy moth, goes through a full transformation, developing from an egg into a larva (caterpillar), pupa, and then an adult. Eggs of the sponge moth typically hatch around the end of April through mid-May. 

Normally, the larva, or caterpillar, phase lasts approximately seven weeks. The weeks in May and June see the maximum activity from the larvae. Throughout late June and early July, the individual larvae develop into pupae and stay in this stage for one to two weeks. 

Adults begin to come out in late June through mid-July, and they may continue into August. The caterpillar molts three or four times as it matures. For this creature to grow, it must lose its skin. 

The term “instar” refers to the time between each molt. Larva in their first instar are tiny and can be challenging to see. Larva in their fourth and fifth instars are enormous, and they have appetites to match. These latter instars are responsible for nearly all of the defoliation that occurs.  

Spongy moth adults don’t eat. The adults just have one purpose in life, which is to reproduce, for roughly two weeks. After mating, the female gypsy moth lays 600 to 1,000 eggs in a tightly packed bundle of silk and eggs that resembles the shape of a teardrop. 

Spongy moth larvae

Spongy moth larvae can be spotted on tree branches.

©Beth Schroeder/Shutterstock.com

How to Get Rid of Sponge Moths

When handling caterpillars of spongy moths, it’s beneficial to use gloves. Histamines are little hairs (setae) that these types of caterpillars transport, and in some people, they can create an itchy, red rash. Here are some great ways to get rid of these fluttery pests. 

Burlap Cloth Flap Trap

Think about using a straightforward burlap cloth flap trap for shielding specific trees. This entails wrapping a foot-wide piece of burlap around a tree, knotting it in the center, and sliding the top end over the bottom end. 

This method takes advantage of the caterpillar’s instinct to continue climbing even in the face of the burlap barrier. The moths can be routinely eradicated and eliminated from the accumulating area.

Soap and Water

Consider stepping outside on a sunny day around September to search for groups of eggs on trunks if you have observed spongy moth caterpillars or defoliation throughout the growing season. Push any into sudsy water if you discover any and discard them in the bin or down the toilet. 

Chemical Repellent 

Insecticide sprays can be an alternative if your inspection reveals significant populations of spongy moth caterpillars. There are two main types of pesticides classic chemical sprays and biological sprays incorporating living organisms.

Final Thoughts

Don’t let spongy moths take over your yard! Although they’re known for destroying trees all around the country, there are plenty of ways to tree an infestation. Please keep in mind that certain pesticides and insecticides may not be safe to use around children or domesticated animals.

The photo featured at the top of this post is © iStock.com/Wirestock


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About the Author

Kirstin is a writer at A-Z Animals primarily covering animals, news topics, fun places, and helpful tips. Kirstin has been writing on a variety of topics for over five years. She has her real estate license, along with an associates degree in another field. A resident of Minnesota, Kirstin treats her two cats (Spook and Finlay) like the children they are. She never misses an opportunity to explore a thrift store with a coffee in hand, especially if it’s a cold autumn day!

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