Cooley Spruce Gall Adelgid Adelges cooleyi (Gillette)
	Order and Family:� Homoptera: Adelgidae
	Host Plant where galls produced: Spruce
	Alternate Host Plant with no galls produced: �Douglas-fir
	Damage and Diagnosis: This cone-like gall is� produced on the tips� of new growth of Colorado blue, Sitka and Engelmann spruces (fig. 27).� The gall is green or purplish in color, 1 to 2 inches long, 1/2 to 3/4 inches in diameter and resembles a small pineapple in an early stage of development.� Galls turn brown and are easily visible in winter.� On Douglas-fir, needles become twisted and yellowed (fig. 27).
	Biology: This insect takes two years to complete its life cycle on Douglas-fir and spruce.� Winged adults fly from Douglas-fir to spruce in late July.� Adults lay eggs on spruce that hatch into nymphs that spend the winter on spruce twigs.� Nymphs become active on spruce in early spring just before the buds break.� They develop into adults in May that lay eggs on twigs.� When these eggs hatch nymphs crawl to the base of spruce needles and cause them to produce the characteristic galls.� In mid-summer, galls on spruce open to release winged adults that fly to Douglas-fir to lay eggs.� These eggs hatch into nymphs that overwinter on Douglas-fir.�� After bud break, nymphs become active and start to distort leaves.� They develop into wingless adults in May.� These adults produce offspring that become winged, and wingless adults in July.� Wingless adults remain on Douglas fir and winged adults fly to spruce to complete the cycle.
	Control on Spruce:� The presence of old galls on spruce in the winter suggests that infested Douglas-fir are near enough for adelgids to have laid eggs on spruce the previous summer.� Scout spruce to target trees that need treatment. Apply broad spectrum insecticides to tthe plant just prior to budbreak to kill nymphs that wintered on the plant as eggs.� By killing these nymphs you prevent adults from laying the new generation of eggs on young needles,where galls are formed in late May. Pruning out old galls makes the plant look nice but does not control the problem.
	Control on Douglas-fir:� Look for signs and symptoms that nymphs are present on twigs.� Early signs include the production of waxy fibers by young nymphs. Later in spring needles begin to twist and yellow.� Applications of insecticidal soap or oil can effectively control the nymphs and prevent further twisting.� Broad spectrum insecticides are also effective.
	General control comments: Do not interplant spruce and Douglas fir, since they are alternate hosts of the Cooley spruce gall adelgid.