Fort Collins Tree Care Fort Collins Tree Care  
Dedicated to Tree Preservation
in the Urban Forest
 
Click for a FREE estimate
or call 970.484.3084
Fort Collins Tree Care Fort Collins Tree Care
Click for a FREE estimate
or call 970.484.3084
Dedicated to Tree Preservation in the Urban Forest
Fort Collins Tree Care Fort Collins Tree Care
Click for a free Estimate or call 970.484.3084
Dedicated to Tree Preservation in the Urban Forest
Fort Collins Tree Care
or call 970.484.3084

Damage caused by spruce gall adelgids (woolly aphids)

Spruce Galls are often found on the tips of blue spruce branches and twigs. Very heavy infestations may cause slower or distorted tree growth, but they usually don't harm the tree. The galls are created by small aphid-like insects, the Cooley spruce gall adelgids or woolly aphids. The woolly aphids feed on Douglas fir needles, causing yellowing, bent needles and sometimes the needles drop from the tree.

Cooley Spruce Gall Adelgid damage Ronald S. Kelley, Vermont Department of Forests, Parks and Recreation, Bugwood.org

How to identify spruce gall adelgids (woolly aphids)

Woolly aphids create a gall on spruce trees. The spruce galls look like a 2" to 4" long cucumber growing from a branch, light green in the spring, but turning brown by July as they dry out. The woolly aphid nymphs are light brown to black, have a flat oval shape, and produce a white wax. On Douglas fir trees, the adult woolly aphid looks like a tiny bit of cotton at the base of a needle, about 1mm long, and its feeding causes yellow spots and bent needles.

Cooley Spruce Gall Adelgids Whitney Cranshaw, Colorado State University, Bugwood.org

Life cycle of the spruce gall adelgids (woolly aphids)

Woolly aphids require two hosts to complete their normal life cycle, a spruce tree and a Douglas fir tree.

Female woolly aphids overwinter on spruce trees, under young spruce branches. They mature and lay a few hundred eggs near spruce buds in the spring. These eggs hatch in about 20 days when the buds open and the nymphs move to the base of the new needles and start feeding. The saliva of the woolly aphid larvae causes the spruce tree to form a gall that they can live inside and eat. The galls look like a 2" to 4" cucumber-shaped growth, starting off green in the spring and early summer and turning brown when they dry out.The woolly aphids mature by mid-summer, when the galls dry out, open and release the winged adults. Most of the adults will fly to Douglas fir trees.

The woolly aphids lay eggs on the Douglas fir needles. The young feed and reproduce, creating several generations by late summer, when some of the woolly aphids grow wings and fly to a spruce tree and lay eggs. Some of them continue breeding and overwinter on the Douglas fir trees.

Cooley Spruce Gall Adelgids Whitney Cranshaw, Colorado State University, Bugwood.org

How to control the spruce gall adelgids (woolly aphids)

The spruce gall is usually harmless and control is not needed, but you may want control them to prevent aesthetic problems.The woolly aphids need both Douglas firs and spruce trees, so the population will be reduced if you have only one or the other type of tree. The best time to spray your spruce tree with insecticide is in the spring before new growth appears or in the fall when the woolly aphids have returned to the spruce tree, because insecticides are not very effective after they have moved into the galls.

Spruce Gall Cheryl Moorehead, individual, Bugwood.org

 
International Society of Arboriculture Colorado Weed Management Association Tree Care Industry Association Fort Collins Tree Care Inc.
301 E. Douglas Road
Fort Collins, CO 80524
970.484.3084
Fort Collins Tree Care Inc.
301 E. Douglas Road
Fort Collins, CO 80524
970.484.3084
International Society of Arboriculture Better Business Bureau Colorado Weed Management Association Tree Care Industry Association
website design by FortCollinsWebWorks.com