Are Your Trees Being Destroyed by Gypsy Moth Caterpillars?

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A spongy month caterpillar, with its distinctive rows of blue and red dots, hangs off a leaf.

Previously referred to as a “gypsy moth”, Lymantria dispar or spongy moth is an invasive and destructive pest found in New York state.

Its name refers to the spongy egg masses that this moth lays.

In this article, we’ll describe what the moth looks like in various life stages, share which trees or plants it is most likely to harm, advise you on what to do to prevent or treat it on your property, and more.

Keep reading to learn about this insect pest that can impact both trees and shrubs.

Male and female adult spongy moths on display in a museum in Japan.
The male spongy moth is displayed on the left, while the female is on the right.

What is the Spongy Moth/Gypsy Moth?

Spongy moth is a non-native invasive insect that spends most of its life (10 months) as an egg in an egg mass. These egg masses are easily transported on firewood, vehicles, or other surfaces.

The moth originated from Europe, Asia, and North Africa and was first spotted in North America in Massachusetts in the 1800s. In fact, it was brought here on purpose to aid in silk production! However, it has since spread across the Eastern United States and Canada and can defoliate trees and shrubs.

There are two types of the moth that are currently invading North America: Flighted Spongy Moth Complex or FSMC (formerly known as Asian gypsy moth), and Spongy Moth (formerly known as European gypsy moth). The latter is the kind most prevalent in the Eastern United States.

How is the Spongy Moth/Gypsy Moth Destructive?

Spongy moth populations are not picky about the trees and plants that they impact. In fact, over 600 plant species have been negatively impacted by this insect pest. The larvae can completely defoliate trees, which can leave the trees stressed and more susceptible to other attacks.

In some instances, the spongy moth caterpillars have defoliated the same trees two years in a row, which can lead to tree death. Entire forests, orchards, or landscapes can be (and have been) destroyed thanks to the moth and its hungry larvae.

What Trees and Plants Do Spongy Moths/Gypsy Moths Destroy?

Over 600 plant species have been noted as a type that the spongy moth larvae feed on. However, there are certain trees in New York that they tend to affect more.

These include:

  • Oak
  • Maple
  • Apple
  • Crabapple
  • Hickory
  • Basswood
  • Aspen
  • Willow
  • Birch

Spongy moth caterpillars feed on the new leaves that appear on trees each spring. They seem to prefer oaks over all other kinds of trees but will eat most kinds of foliage.

When the preferred food sources are scarce, the moths can also feed on the needles of conifer trees, including:

  • Pine
  • Spruce
  • Hemlock
  • Other coniferous trees

On the left, a spongy moth caterpillar on a fallen tree leaf. On the right, a spongy moth adult on a fallen tree leaf.

How to Spot and Recognize Spongy Moths

Spongy Moth Caterpillars

You’re most likely to spot spongy moths in their larval stage, while they are still caterpillars. The caterpillars will hatch around May in New York and will grow to around 2 ½ inches long. The caterpillars have distinctive rows of blue spots and lower rows of red spots on their backs.

Spongy Moth Adults

The moths will emerge starting in July. Female moths are white and have brown markings, while male moths are brown.

Spongy Moth Egg Masses

The rest of the year, you should be looking for moth’s egg masses, which are light brown and covered with hair. Egg masses can be on any smooth surface, from tree branches to outdoor furniture or vehicles. They can be confused with spotted lanternfly egg masses, another invasive, destructive insect currently affecting trees and plants in New York.

gypsy moth adult females and spongy moth egg masses on a tree trunk in New York.
Spongy moth adult females and spongy moth egg masses on a tree trunk in New York.

How to Control Spongy Moths

There are several ways to prevent this destructive pest from spreading further.

Follow all Quarantine Laws

According to the USDA, “If you are moving from a spongy moth quarantine area to a non-quarantine area, you must inspect your outdoor household items for the [spongy] moth and remove all life states of this destructive insect before you move. You and your moving company may face penalties if you are required to inspect but fail to do so.”

All of New York state and many of the surrounding states are under the Federal spongy moth (gypsy moth) quarantine.

Learn more about what to do if you are moving >>

See the Federal Spongy Moth Quarantine interactive map >>

Control Moths on Your Property

Though spongy moths are invasive, they are here to stay. These naturalized insect pests will be more prevalent during some years and less noticeable during other years.

However, that doesn’t mean that you shouldn’t try to prevent them from destroying your trees and plants. There are several ways you can try to control the population of spongy moths on your New York property

Manually Destroy the Insect in All Forms

One of the simplest ways to control the spongy moth population on your property is to manually scrape off egg masses and destroy them, squash any caterpillars on your plants, and step on or otherwise destroy the moths.

The hairs on the caterpillar can cause skin irritation, so be careful when coming into contact with them.

Use Traps (with Caution)

Some property owners choose to use traps to catch spongy moths while they are still in the caterpillar phase. The most common is to use sticky bands around the trunk of affected trees. However, these traps should be used with caution as they can also trap beneficial insects and other wildlife.

Use an Insecticide

Rather than using a broad insecticide, which can harm other insects and wildlife, we recommend using a horticultural or dormant oil to prevent spongy moth infestations.

Contact Hill Treekeepers for more information on how we can help prevent spongy moths on your property. We have our Commercial Pesticide Business Registration and have certified pesticide applicators on staff.

Pest and Disease Treatments >>

Keep Your Trees Healthy

Stressed or sick trees are more susceptible to an attack from a pest or disease, including spongy moths.

By scheduling proper maintenance, keeping your trees well-watered, applying organic mulch, and treating or preventing health issues, your trees will be less likely to be damaged or will be less prone to die if they do become infested.

Learn more about how to prevent and treat tree pests and diseases >>

A spongy moth caterpillar crawls along a tree branch in New York.Contact Hill Treekeepers for Spongy Moth/Gypsy Moth Prevention

Gypsy / spongy moth is here! It’s been spotted in Litchfield county, Dover, NY, and Hopewell. We’re already getting calls from people with defoliated trees. If you suspect or spot spongy moths (gypsy moths) on your property and want to prevent them from damaging your trees, contact Hill Treekeepers for the latest information on spring treatment options.

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Todd Hill

Todd Hill

Todd is the founder of Hill Treekeepers and an ISA Certified Arborist with life-long ties to the Hudson Valley area.

Get the highest quality of tree services for residential and commercial properties in the Hudson Valley area. We look forward to working with you!

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