Nature Lab

Each month, we highlight research MDC uses to improve fish, forest, and wildlife management.

Forest Health

Gypsy Moth Monitoring

“What’s at stake?” asked MDC Forest Entomologist Robbie Doerhoff. “More than 12 million acres of oak-dominated forest.”

She’s talking about Missouri’s annual efforts to monitor the gypsy moth. This European species was accidentally released in the Boston area in 1869, and it has since become one of the most destructive forest pests in the U.S.

Currently, the gypsy moth ranges from Maine to Wisconsin, through northern Illinois, and into Ohio and Virginia. Every year, gypsy moth caterpillars defoliate over a million acres of forest and cost citizens an estimated $868 million in damages.

While Missouri has no current infestations, monitoring efforts detected gypsy moths in Dent and Taney counties in the 1990s. These infestations were successfully eradicated.

MDC Forest Pathologist Natalie Diesel noted that the gypsy moth caterpillar eats 300 species of trees and shrubs, “but it loves oaks.”

After this pest becomes established in a new area, its numbers can periodically reach outbreak levels.

 “Millions of caterpillars devour all the leaves off of trees — even entire forests — in early spring. This feeding damage is a major source of stress, which can make trees vulnerable to an array of secondary insect and disease issues,” Doerhoff said.

“Our traps contain a pheromone lure that attracts male gypsy moths,” Diesel said. “Once inside, moths are captured by the trap’s sticky inner walls.”

Monitoring efforts have captured about 500 male gypsy moths over the last 51 years. “With annual statewide monitoring, we have a shot at eradicating this pest if we detect it early,” Doerhoff said.

Gypsy Moth Monitoring at a Glance

• 1967 - Year gypsy moth monitoring began
• 10 - Number of seasonal monitoring staff
• 2–10 - Number of male gypsy moths detected annually
• 12.2 million - Acres of Missouri oak forests at risk
• 6,000–8,000 - Number of traps deployed every summer

Monitoring partners:

• Missouri Department of Conservation
• Missouri Department of Agriculture
• U.S. Department of Agriculture
• U.S. Army / Fort Leonard Wood
• Missouri National Guard