Cooley Spruce Gall Adelgid

Adelges cooleyi (Gill)

From: Field Guide to Diseases and Insect Pests of Idaho and Montana Forests, USDA Forest Service Northern Region, Publication Number R1-89-54

Hosts. – Douglas-fir and spruce.

Distribution. – On hosts throughout Idaho and Montana.

Damage. – On Douglas-fir, nymphs suck out the juice of current needles which turn yellow and fall off. On spruce, nymphs form galls on the tips of twigs and branches.

Identification. – Look for galls on spruce. In late spring, the unopened galls are green with shades of pink or purple. Nymphs may be found inside them. Open galls, found in late August, are brown, dry, and resemble small cones (fig. 105). Look f or oval, black nymphs with a white, waxy fringe or oval, dark brown adults covered with white, woolly wax on current Douglas-fir needles during spring and summer months (fig. 106). See Table 4 for comparison of Cooley spruce gall adelgid damage with that of needle casts and midges.

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Figure 105 - Galls on branch tips contain developing Cooley Spruce Gall Adelgid nymphs. Opened galls resemble small cones.	Figure 106 - Alternate stage of Cooley Spruce Gall Adelgid on Douglas-Fir appear as tufts of cotton on needles and black "dots" of the crawler stage on new growth.

Similar damages. – On Douglas-fir, damage may be similar to that caused by Douglas-fir needle midge, Rhabdocline, Swiss needle cast, or aphids.

Link to Table 4 – Comparison of Needle Problems of Douglas-Fir

Link to Images in Forestry Images

References.

Anonymous. 1982. For. Insect & disease identification and management. USDA For. Serv.,Northern Region; Idaho Dept. of Lands, Insect and Disease Control; Montana Dept. of State Lands, Division of Forestry. 192 p.

Furniss, R. L., and V. M. Carolin. 1977.  Western For. Insects. USDA Forest Serv., Misc. pub. 1339, 654 p., illus.

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