Hemlock Woolly Adelgid
1. Hemlock woolly adelgid completes two generations per year on hemlock. During March and April, adults of the overwintering generation lay 50 to 300 eggs each in a cottony mass on the young twigs. Nymphs (called crawlers) hatch from these eggs in April and May. Within a few days, they settle on the twigs near the base of the needles where they insert their piercing and sucking mouthparts. There they feed and remain throughout their development. This spring generation matures by the middle of June. Some of the adults produced at this time are winged individuals that are unable to reproduce on hemlock. Other adults produced at this same time are wingless and are able to reproduce. In the middle of June these wingless adults lay 50 to 300 eggs each in a cottony mass on the twigs. Crawlers hatch in early July and settle on the new growth. They soon become dormant until the middle of October, when feeding resumes. Nymphs feed and develop during the winter and mature by spring.
2. The hemlock woolly adelgid survives by sucking the sap from hemlock trees. In eastern North America, it is a destructive pest that poses a major threat to the eastern hemlock (Tsuga canadensis) and the Carolina hemlock (Tsuga caroliniana).
3. In North America the adelgid has been causing damage to Carolina and Eastern Hemlocks along the East Coast extending from North Carolina to Maine. The natural range of eastern hemlock extends from Georgia to Maine, west to Michigan and Minnesota.
4. The Hemlock Woolly Adelgid is native to Asia where it is not a problem to native hemlocks. It was introduced via infected nursery stock to the United States in the early 1950s near Richmond, Virginia.
5. The hemlock woolly adelgid can kill a tree very quickly depending on the population of HWA on the tree. Heavy populations will cause a tree to die quickly. Some trees survive years, but in a thin sickly state.
6. Several methods of control are being researched....