A tiny sap-sucking insect related to aphids, causing widespread death and decline of hemlock trees in the eastern United States. In its native range, HWA is not a serious pest because populations are managed by natural predators and parasitoids and by host resistance. Without these natural defenses, the adelgid poses a very serious threat to the sustainability of Eastern Hemlocks. The egg sacs of these insects look like the tips of cotton swabs clinging to the undersides of the current year’s hemlock twigs.