Balsam Wolly Adelgid
Egg-The ovoid, amber egg is usually found in a mass of waxy strands and eggs.
Nymph-The newly hatched nymph is called a crawler. It is a small (0.35-mm), amber, flattened insect with red eyes. As it matures, the older nymph generally resembles the adult except for size. The overwintering form (neosistens) of the crawler flattens itself to the bark and secretes a waxy fringe at the body margin.
Host Plants -Balsam and Fraser firs are the host plants for balsam woolly adelgids in the eastern United States. Apparently all species of firs (Abies spp.) are infested by this pest. However, while some species are very tolerant (Noble fir), other species are devastated by the pest (balsam, Fraser, and sub-alpine firs)..
Damage -Balsam woolly adelgids, introduced from Europe or Asia, were first noticed in Maine in 1908. Billions of feet of fir timber have been killed by balsam woolly adelgids in North America. Balsam woolly adelgids secrete an irritating salivary substance, which is injected into the host as they feed. This substance causes unusual growth (swelling or "gouting"), which distorts the normal growth pattern. Branchlets thicken, twist, and bend down at the ends. The main stem tapers rapidly at the top, and the tip bends or becomes flattened. A heavy stem attack may kill an otherwise healthy tree in 3 or 4 years. The wood of heavily infested trees becomes brittle and darkened.
Life History -Balsam woolly adelgids overwinter as first-stage nymphs. In spring, development resumes and the insects mature about the time the buds begin to break (mid-April). Eggs are deposited in spring and summer. Each egg is attached to the bark behind its mother by a waxy thread. In warm weather the eggs hatch in a few days. Up to 248 eggs are produced by each female. By fall all stages may be present. Three generations occur each year in North Carolina. Balsam woolly adelgids feed anywhere on the tree from which they can reach the parenchyma of the cortex (living portion of the bark) with their mouthparts.
Low winter temperatures and a small, brown beetle, Laricobius erichsonii, are important natural agents of control. Silvicultural methods (clean cutting, prompt salvage in winter, short rotation, etc.) will lessen the effect of the pest. For specific chemical controls, see the current state extension service recommendations.