Giant conifer aphid
Cinara spp.
57 host plants
Last updated
Large, dark brownish-black aphids (up to 0.2 inch) congregate in visible colonies on the undersides of fir branches throughout Western Washington, especially from midsummer into fall. Infested true fir species like grand fir and white fir develop sticky honeydew coating the foliage, with sooty mold often following. Heavily infested trees show yellowing needles and reduced growth vigor; young seedlings may be killed outright. Look for large clustered aphids.
Monitor fir trees for colonies during summer; lady beetles and lacewings naturally suppress Cinara aphids. Conserve these predators by avoiding broad-spectrum insecticides. For young landscape firs, blast colonies with strong water spray or apply neem oil to affected branches. Horticultural oil sprays in early fall reduce overwintering populations without harming beneficial insects.
Quick Reference
Cultural Controls
- biological control Many parasites and predators attack aphid.
- Monitor the proportion of aphid mummies to unparasitized adults and the number of predators such as lady beetles.
- If the biocontrol agents appear to be gaining control, avoid sprays which would disrupt this system.
- Most products available for aphid control are highly disruptive of natural enemies.
- Management-cultural control Aphid populations tend to be higher in plants that are fertilized liberally with nitrogen.
- Prune out suckers...