Hemlock Woolly Adelgid

An adult individual body length is typically 0.8 mm, and is oval in shape. The tiny brown-colored insect has four thread-like stylets that are bundled together and function as a mouthpart. Three times the length of its body, the stylet bundle pierces the host plant's parenchymatic ray tissue to derive nutrition from stored reserves. It may also inject a toxin while feeding. The resulting desiccation causes the tree to lose needles and not produce new growth. Hemlocks stricken by HWA frequently become grayish-green rather than a healthy dark green. In the northern portion of the hemlock's range, death typically occurs 4 to 10 years after infestation. Trees that survive the direct effects of the infection are usually weakened and may die from secondary causes. The presence of HWA can be identified by its egg sacs, which resemble small tufts of cotton clinging to the underside of hemlock branches. In North America, the hemlock woolly adelgid asexually reproduces and can have two generations per year. Both generations are parthenogenetic and exclusively female. In its native Asian habitat, a third winged generation called sexupera occurs. This generation's sexual reproduction requires a species of spruce not found in the Eastern United States. Between 100 and 300 eggs are laid by each individual in the woolly egg sacs beneath the branches. …