Post Outbreak Gypsy Moth (Lymantria dispar) Egg Mass Survey in Northern New York

Abstract

Gypsy moths (Lymantria dispar) are an invasive species whose initial spread centered in Massachusetts and quickly advanced throughout the Northeast before reaching the mid-Atlantic, Michigan, and Wisconsin. These large-scale defoliators serve as a cyclical wave of disturbance with varying annual intensity and periodic peak years. Gypsy moth management is stage-specific, so understanding the life cycle is essential in order to facilitate the best management practices. In spring 2021, I surveyed gypsy moth egg mass densities in forested areas within Clinton and Essex County New York to determine if pest outbreak thresholds were met in the region. Across nine sites, which included local landowner properties, state parks, and wildlife management areas, I followed the NYS DEC egg mass sampling protocol. At each site, four plots were established and metrics collected included tree species, tree diameter, bark texture, and egg mass abundance and vertical distribution. Threshold infestation levels were met in five of the nine sites and Wickham Marsh forest was the most heavily infested. The most impacted trees were eastern white pine (Pinus strobus) and northern red oak (Quercus rubrum), specifically those individuals with an average diameter of 44.7 cm and vertically cracked bark. The data collected in this survey will inform regional biologists of more heavily damaged forests and land owners in order for them to develop a management plan for gypsy moths in the North Country.