Egg-The black, oval egg is laid in a cottony mass of waxy strands.
Nymph-The yellowish- to bluish-green nymph grows to a length of about 1 mm. An exposed nymph is usually covered by cottony, waxy strands, which may obscure the nymph.
Host Plants -Norway and white spruce are the favored hosts of the eastern spruce gall adelgid, but it has been found on red, black, Engelmann, and Colorado blue spruce as well.
Damage -The eastern spruce gall adelgid causes minor physiological damage to its host plants unless the host is severely infested. Severely infested trees may decline in vigor. The primary damage is that of reduced aesthetic value of host plants in nurseries, Christmas tree plantings, or landscapes. The galls are 1.5 to 2 cm long and pineapple shaped. In summer the galls dry out and turn brown. The stem is often distorted at the gall.
Life History -Eastern spruce gall adelgids overwinter as partially grown females (stem mothers) near or at the dormant buds. In early spring the stem mothers mature and lay 100 to 200 eggs surrounded by cottony or woolly wax. The eggs are laid about the time the buds break. About 10 to 14 days later, the nymphs hatch and begin to feed at the bases of the needles. Their feeding causes a pineapple-shaped gall to form in the new twig. The nymphs mature in cells inside the gall until the gall dries out and splits open in summer. Although winged, the females usually stay on the host and soon lay up to 60 eggs in a cottony or woolly wax, usually at the tips of needles. The nymphs from this summer generation of eggs are the overwintering forms. There is one generation per year, and there are no males.
The overwintering nymphs should be controlled in early spring before new growth begins. For specific chemical controls, see the current state extension service recommendations.
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