Survival of hemlock woolly adelgid (Homoptera: Adelgidae) at low temperatures

Abstract

The potential spread of hemlock woolly adelgid (HWA) into northern New England was studied by examining the winter coldhardiness of a northerly population. Sistens were collected at three times during the winter and subjected to temperatures typical of those during winter in the next coldest USDA plant coldhardiness zone. When all exposure times were combined, the percentage of live adelgids after subzero treatment declined significantly as temperature decreased. In most cases, fewer HWA were alive after treatment as exposure time increased.