Hemlock Woolly Adelgid (HWA) is believed to have been introduced into the United States in Virginia around 1951, probably from Japan or China. HWA first appeared in Rabun County, Georgia in 2003 and has moved west through the state almost to the I75 corridor to date, and is expected to continue moving west at the same rate.
Hemlock Woolly Adelgid, scientific name: Adelges Tsugae, is a very small juice sucking bug approximately 1/32 to 1/16 of an inch is size. This bug is infesting all hemlock trees in the Eastern United States and is fatal to the Eastern Hemlock (Tsuga Canadesnsis) and the Carolina Hemlock (Tsuga Caroliniana). Currently the HWA is negatively affecting hemlock health and longevity in 16 eastern states from Maine to Georgia and as far west as Minnesota.
Adelgids are related to aphids and have a similar, complex life
cycle. The HWA is parthenogenic, meaning that all
individuals are female and produce offspring without mating. In North
America there are 2 generations per year.
In the spring, adelgid hatch from a white, cottony egg sac that may
contain as many as 300 eggs. The adelgid crawls around until they
settle at the base of a needle, and begin to suck nutrients from it.
Their saliva is toxic to the tree, and eventually causes needle drop
and twig die back. They will usually remain at that feeding site for the
rest of their lives. They become adults and then produce an egg sac which hatch Duran an extended time period of February through June
In the Southeastern United States, infested hemlocks mortality rate is from 3 to 6 years. Some researchers stress that six years is highly optimistic as their research shows that the southern warm winters does not slow the HWA's progress.