If I chemically treat my hemlocks, will it harm the beetles?

Since the beetles do not ingest any part of the hemlock, they will rarely directly be killed by the insecticide, but they will lose their food source as the HWA die. This is a very delicate balance we work to keep in our treatment areas. For private landowners, in most circumstances, we suggest chemically treating any tree you do not want to risk losing or see decline in health.