Some of the adults produced at this time are winged individuals that are unable to reproduce on hemlock. Therefore, they leave the hemlock tree is search of spruce, and because no suitable spruce host is available in the eastern United States, they soon die. Other adults produced at this same time are wingless and are able to reproduce on hemlock. In the middle of June these wingless adults lay about 100 eggs each in a cottony mass on the twigs. Crawlers which hatch in early July settle on the new growth and soon thereafter become dormant until the middle of October when feeding resumes.
Nymphs feed and develop during the winter and mature by spring.
Because HWA can damage trees so quickly, it is important to detect infestations early. Frequent visual inspection is the most effective means of determining whether or not a hemlock is infested. It is particularly noticeable in spring on the undersides of the young twigs. Care should also be taken when moving plants, logs, firewood, or bark chips from infested areas onto an non-infested property, especially from March through June when adelgid eggs and crawlers are abundant. Cleaning vehicles, clothing, etc.