Cooley's Spruce Gall Adelgid

By The Old House Web

Cooley's Spruce Gall Adelgid

List of files and visuals associated with this text.

The immature females overwinter on spruce trees. The female matures in the spring and lays eggs on the branch tips. The eggs hatch and nymphs move to the new growth and feed at the base of the needles. The feeding causes formation of a gall that encloses the insects. In midsummer an opening forms at the base of each needle on the gall. The insects leave the gall through these openings and become winged females. They fly to douglas fir or a spruce and feed on these trees as though they were woolly aphids.

The most visible symptom is the galls formed at the branch tips. The branch tips appear to have swollen and drooped. They are sometimes described as small 'cones'.

Use diazinon, Sevin, malathion, Orthene, or dormant oil. Sprays must be applied before the insects are enclosed in the gall.

Visuals associated with this text.

Visual title - Visual size Visual title - Visual size
Cooleys Spruce Gall Adelgid - 46K Cooleys Spruce Gall Adelgid - 57K
Cooleys spruce gall adelgid on spruce - 47K Cooleys spruce gall adelgid on douglas-fir - 65K
Cooley spruce gall adelgid, early stage - 32K
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