WSDA Blog

Date: Wednesday, January 31, 2024

Author: Karla Salp

WSDA celebrates 50 years of protecting the Evergreen State from spongy moth

Each summer, dozens of temporarily employed but always committed people swell the ranks of the Washington State Department of Agriculture’s Pest Program as seasonal trappers. For five decades, these dedicated trappers and a handful of permanent staff have come together to continue the long-held record of preventing spongy moth* – one of the worst invasive pests ever introduced into the United States - from establishing in Washington State.

Keeping spongy moth from establishing in Washington is really about one thing: saving our trees. Depending on the type of moth, spongy moths can eat from 300-500 types of trees and shrubs – including the towering evergreens for which our state is known.

Spongy moth is permanently established in over 20 eastern states. When those states experience outbreaks of this destructive moth, the results are devastating. Entire forests are stripped of their leaves. With repeated years of this defoliation, the trees can be killed. In 2016-2017, New England saw millions of trees killed from heavy caterpillar feeding. The damage was so widespread that a third of the state of Rhode Island was defoliated – damage so extensive NASA satellites could record it.

Given the moth’s well-known track record of having substantial negative impacts on trees in neighborhoods, parks, and forests, the WSDA began trapping for the pest and caught the first moth in 1974. It wasn’t until five years later that the department conducted its first eradication. Since then, WSDA has trapped spongy moths nearly every year – catching as many as 1300 moths in 1983, though most years see fewer than 100 moths caught.

Keeping this aggressive invasive pest at bay for 50 years is a big deal. To celebrate, we’ll be sharing about spongy moth and our program’s work all year long! Stay tuned to our social media channels for more about spongy moth, or visit agr.wa.gov/moths to learn more now.

Image captions

1. First day of trapping in the 1980s. Trappers arrive to pick up their state vehicles and trapping supplies. 
2. John Lundberg with an enthusiastic supporter of spongy moth eradication. Not everyone is always so supportive, but people who have lived in states where the pest is established are often the top supporters of preventing spongy moths from establishing in Washington State. 
3. Article in the Skagit Valley Herald about the work of the spongy moth program (formerly known as gypsy moth). 

* Spongy moth was formerly known as gypsy moth