Distribution of Adelges tsugae (Hemiptera: Adelgidae) within an eastern hemlock tree

Within-tree distribution of an insect pest can help to determine where to sample and apply control measures. This study was conducted to characterize the within-tree distribution pattern of Adelges tsugae (Hemiptera: Adelgidae) on eastern hemlock. A total of 21 trees with A. tsugae were randomly selected in Black Water Fall State Park (Davis, WV) and 24 branches in each tree were cut with regard to six vertical heights and four directions (i.e. north, south, east, and west). Branches were brought to the laboratory and the number and location of individual ovisacs within a branch was recorded and mapped. The results of this study showed that A. tsugae ovisacs were more frequently found at the tip of a branch regardless of branch directions. However, more ovisacs were generally found in the vertically middle and high rather than low branches within a tree. The results of this study will be used to determine sampling units for monitoring A. tsugae on eastern hemlock.