Impact of Hemlock Woolly Adelgid and Elongate Hemlock Scale on Early Seasonal Development of Eastern Hemlock

Herbivores can have a significant impact on plant host development. While altered plant development most commonly results from defoliation, some causes are more cryptic. Effects on development can be difficult to detect in long-lived woody plant species. Hemlock woolly adelgid is a piercing-sucking herbivore that has been previously been observed to have substantial effects on eastern hemlock. Observations of bud break were carried out on a three-day-on, one-day-off rotation from April through May in 2016 and 2017. We found that hemlock woolly adelgid delayed bud break in eastern hemlock. Our findings suggest that piercing-sucking herbivores can also significantly affect the early development of long-lived woody plant species.