Conservation Outdoors

Conservation: Aerial Treatments to Curb Spread of Gypsy Moths

Aerial mating disruption application for the National Gypsy Moth Slow the Spread Program by Air Tractors

By Emma Castleberry

Since 2000, the state of North Carolina has been part of a nationwide effort to curb the spread of the gypsy moth, an invasive European species whose larvae feed on the leaves of more than 300 different species of trees in North America. Since 1982, there have been active efforts to monitor the population of gypsy moths in the state, and more than 100 intervention programs have been implemented. The current proposed treatments will use an organic product applied by low-flying aircraft. “We typically get a lot of questions about the product we plan to use and if it is harmful to people or animals,” says Allison Ballantyne, who manages the state’s gypsy moth program. “The product is certified organic, specific to the gypsy moth and harmless to people and animals.”

In the western part of the state, the planes will distribute a pheromone that disrupts how the moths communicate with each other for mating purposes. “When an area is saturated with this pheromone,” says Ballantyne, “it simply prevents the male moth from locating the flightless female to mate. Disrupting this part of the moth life cycle allows us to control the pest in a non-lethal manner.”

Gypsy Moth caterpillar collected in western Virginia. Photos by Tom Coleman of USDA Forest Service

The story of this invasive species begins as many do, with a well-meaning entomologist. Etienne Leopold Trouvelot introduced the gypsy moth to the US near Boston in 1869. He hoped to establish a silkworm industry in North America by interbreeding the gypsy moth with native caterpillars. A storm overturned the caterpillar enclosures in his backyard and released them into the wild and, with no natural predators, the gypsy moth larvae began their munching destruction. They have defoliated more than 75 million acres since 1970.

Fortunately for North Carolina, much of this damage is localized to the northeastern part of the country.

Fewer than 6,000 acres in WNC have verifiable, reproducing gypsy moth populations, and the state has quarantined two regions in the northeastern part of the state: the whole of Currituck County and a portion of Dare. Gypsy moth quarantine places regulations on the movement of certain items like trees, firewood, recreational vehicles and mobile homes.

Ballantyne attributes the state’s relative success in part to its collaboration with the national Slow the Spread Trapping and Treatment Program. “Each year, we conduct a state-wide trapping survey that provides us with up-to-date gypsy moth population data,” says Ballantyne. “For areas with indicated reproducing populations, treatments are planned for the following year, which prevents this pest from establishing itself throughout our state.”

Individuals also play an important role in curbing the spread of this pest. “Although the gypsy moth can spread relatively short distances on its own, it is also unintentionally transported by humans because the female moth will lay her egg mass on a variety of items,” says Ballantyne. “When moving or traveling from an infested area to an uninfested area, please inspect things like firewood, lawn furniture, outdoor toys and vehicles for egg masses before travel.”

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