Balsam twig aphid

On true firs (grand fir, silver fir, white fir) and balsam fir you will see honeydew-covered twigs with small glossy black aphids clustered at twig terminals in late summer and fall. Infested foliage shows sticky residue and sooty mold coating. Look for the aphids concentrating on new growth during August through October in Western Washington conifer landscapes.

Prune and remove infested twig terminals before aphids produce overwintering eggs. Horticultural oil applied in March or April targets overwintering eggs on bark. If populations persist, spray insecticidal soap in late August when new generations appear. Preserve natural predators by avoiding broad-spectrum insecticides. Damage is typically cosmetic.