Aphid (Manzanita leafgall aphid)
24 host plants
Last updated
Check manzanita and kinnikinnick leaves in spring for thickened gall-like growths starting bright red, turning brown. These galls result from tiny aphids (0.04 to 0.06 inch) feeding inside leaf tissue, deforming rather than creating holes. Look for distorted, almost unrecognizable leaf structures at branch tips on arctostaphylos species throughout Western Washington.
Prune green galls while growing and before browning; this removes aphids and costs nothing. Syrphid fly larvae naturally parasitize aphids inside galls, so avoid insecticides that kill beneficials. Use insecticidal soap on young galls before hardening; time applications for early May to catch susceptible stages. Cosmetic damage is primary concern; tree vigor rarely suffers.
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...