Bug Off: Agency hard at work to keep invasive moth out of N.C.

by | Jan 23, 2019

The gypsy moth is not a new problem to the United States. Introduced from Europe to the Boston area in the 1860s, this invasive insect is now considered the worst pest of hardwood trees in eastern United States. Gypsy moth caterpillars can completely strip a tree of its leaves and when this occurs repeatedly, trees can weaken or die.

Since the 1980s, gypsy moth has been knocking at North Carolina’s door. In 1988, Currituck and part of Dare County became infested and a quarantine was put in place, regulating the movement of specific articles on which gypsy moth eggs cases may be laid and accidentally transported.  Despite that initial venture into our state, thirty years later, there are no other counties quarantined or considered infested by gypsy moth. This is a feat that defies previous predictions of spread and is owed entirely to vigilance and response in keeping this moth out of N.C.

Widely viewed as a success story, the spread of gypsy moth is being slowed in the east and Midwest by the Slow the Spread Program. In North Carolina, the NCDA&CS Gypsy Moth Program cooperates with the national Slow the Spread program and sets traps statewide to detect if and where gypsy moth populations are popping up. Based on trapping results and supplemental visual surveys, areas with a budding infestation are treated. In a sense, spot fires are put out as they cross the state line.

This past trapping season (summer 2018), 594 gypsy moths were captured in traps across the state. That may sound like a lot, but it is a drastic decline from previous years when 1,613 moths were caught in 2017, 7,235 moths were caught in 2016, and 2,021 moths were caught in 2015. Because traps use the female moth’s sex pheromone as a lure, only male moths respond and are therefore captured. Many of these captures may occur from stray moths or moths blown in during a weather event and therefore not representative of a growing population. Essentially, capturing moths in an area is not sufficient criteria for the threat of a reproducing population. So, while these numbers might seem high, the actual threat is much less.

Due to the location of this season’s positive traps and pressure from the moving front in other areas of the U.S., the N.C. Gypsy Moth Program will treat one area this year. Just south of the Virginia state line, 1,231 acres in Surry County will be treated with the female sex pheromone, which inundates the area, disabling the ability of the males and females to find each other and therefore reducing mating and egg laying. This treatment is safe to non-target organisms as it is specific to the gypsy moth.

While the fight is a long one, it’s one we are winning here in N.C.! Bug off, gypsy moth!

Gypsy moth treatments are administered via aircraft. Photo: NCDA&CS Plant Industry Division.