USDA Warns Asian Gypsy Moth Could Cause Widespread Damage to Country's Natural Resources

"Murder hornets" have received a lot of media attention lately but the federal government has warned another invasive pest—the Asian gypsy moth—could cause widespread damage to the country's natural resources.

The U.S. Department of Agriculture's (USDA) Animal and Plant Health Inspection Service says the insects already have a presence in the U.S.—sightings have been reported in Washington State, Oregon, Georgia, Oklahoma and South Carolina—but fears they could become a permanent feature.

"If they would become established here, they could cause serious, widespread damage to our country's landscape and natural resources," the USDA said.

Like the Asian giant hornet (or "murder hornet") these insects are thought to have arrived in the U.S. via shipping containers and other cargo from their native continent. Unlike the Asian giant hornet, Asian gypsy moths are not a single species, but include Lymantria dispar asiatica, Lymantria dispar japonica, Lymantria albescens, Lymantria umbrosa, and Lymantria postalba.

The biggest threat they pose is to native plants. Female moths can lay hundreds of eggs that transform into caterpillars with large appetites, able to decimate large sections of forests, orchards and other patches of vegetation. Large infestations can defoliate trees and shrubs, the USDA explained, leaving the plant susceptible to disease.

The USDA also warned that the female moths are strong fliers, with an ability to travel long distances, increasing the possibility of migrating to neighboring states.

Plants and shrubs on the USDA at-risk list include species of sweetgum, apple, popular, oak, willow and linden trees.

The USDA said: "In the eastern United States, European gypsy moths defoliate an average of 700,000 acres each year, causing millions of dollars in damage. If AGM were to become established in our country, the damage could be even more extensive and costly."

Gypsy moth (Lymantria dispar) on a raspberry leaf closeup stock photo
Stock image of a gypsy moth (Lymantria dispar) on a raspberry leaf closeup stock photo. The USDA warns the moths could cause widespread damage to the country's resources if they become established. grannyogrimm/iStock

The first Asian gypsy moth spotted in North America was found in British Columbia, Canada. Since then, they have been spotted in Washington and Oregon. This persistent moth has been identified and eradicated at least 20 times between 1991 and 2014.

The most recent sightings were in Washington, where three hybrid Asian gypsy moths were trapped at Boulevard Bluffs. A Hokkaido gypsy moth, trapped in Woodway, is the first of its species to be seen in the U.S.

In response, Gov. Jay Inslee signed a proclamation on 15 May warning that the Asian gypsy moth and Asian-European hybrid gypsy moth could cause infestations in Snohomish County, northwest Washington.

"This imminent danger of infestation seriously endangers the agricultural and horticultural industries of the state of Washington and seriously threatens the economic well-being and quality of life of state residents," the proclamation stated.

The state plans to deal with the invaders by dropping more than 655 gallons of insecticide over the Woodway and Boulevard Bluffs areas. The first treatment is scheduled for today (15 May) to coincide with gypsy moth caterpillars' emergence in the spring.

The USDA has said that ongoing surveys in Washington, Oregon, Georgia, Oklahoma and South Carolina will keep an eye on any potential infestations and take action if needed. The department is also asking members of the public to report any sightings of adult moths, their caterpillars and egg masses, as well as defoliated trees.

The website explains that egg clusters can be identified as a mass of " buff or yellowish fuzz and average 1.5 inches by three-quarter inches wide, but can be as small as a dime."

Recently hatched caterpillars are tan in color, and roughly an eighth of an inch long. As they get older and bigger, they develop two rows of blue and red spots along their backs. Coloring can range from yellow to black.

Adult males have gray-brown wings that span 1.5 inches, whereas females are whiter and have a larger wingspan at 3.5 inches.