Hosts and Symptoms of Major Aphid and Adelgid Pests of Christmas Trees

Chal Landgren and Franki Porter
Revised: 
March 2019

Hosts and Symptoms of Major Aphid and Adelgid Pests of Christmas Trees

Tree and symptoms

Pest

Douglas-fir (Pseudotsuga)

Aphids without much waxy covering. Producing large amounts of honeydew, which may be attractive to ants and yellow jackets, or covered by sooty mold.

conifer aphid (Cinara spp.)

“Pepper” flecks (crawlers) on needles in late spring and/or white cottony tufts on needles before budbreak or after about mid-June.

Cooley spruce gall adelgid (Adelges cooleyi)

True fir (Abies)

Aphids without much waxy covering. Producing large amounts of honeydew, which may be attractive to ants and yellow jackets, or covered by sooty mold. Two species, C. occidentalis and C. abietis, are found in noble fir. The former is found typically on the tree bases on 1-3 year old branches and can be quite damaging, the latter is a large conspicuous aphid found on the leaders throughout the year.

conifer aphid (Cinara spp.)

Swelling of branch nodes. Very small waxy adelgids may or may not be found. Trunk, branches, or twigs may be covered with white, waxy secretions in heavy infestations.

balsam woolly adelgid (Adelges piceae)

Twisting of new growth. Small greenish yellow or bluish gray aphids. Wax and honeydew may be present, matting needles together.

balsam twig aphid (Mindarus abietinus)

Tree above-ground appears stunted and off-color. Below ground there may be colonies of white colored aphids feeding on roots, often tended by ants.

conifer root aphid (Prociphilus americanus)

Spruce (Picea)

Aphids without much waxy covering. Producing large amounts of honeydew, which may be attractive to ants and yellow jackets, or covered by sooty mold.

conifer aphid (Cinara spp.)

Pineapple-shape galls or cones on branch tips

Cooley spruce gall adelgid (Adelges cooleyi)

Twisting of new growth. Small greenish yellow or bluish gray aphids. Wax and honeydew may be present as well.

balsam twig aphid (Mindarus abietinus)

Old (more than 1 year old) needles shed, especially on lower, shaded portions of tree. Aphids peak in late winter (February–March), decline toward summer. Small, green aphids.

spruce aphid (Elatobium abietinum)

Pine (Pinus)

Aphids without much waxy covering. Producing large amounts of honeydew, which may be attractive to ants and yellow jackets, or covered by sooty mold.

conifer aphid (Cinara spp.)

White flocking on bark of branches and trunk. Trunk may appear “snow covered.”

pine bark adelgid (Pinus strobi)