How to Manage Pests

Pests in Gardens and Landscapes

Seasonal development and life cycle—Woolly apple aphids

Woolly apple aphids overwinter as adults on roots and aerial parts of apple trees. By early summer, large numbers of nymphs are produced. First-instar nymphs migrate up and down the tree; those from root colonies may move up the tree and those from aerial colonies may move to the roots, entering through cracks in the soil. First-instar nymphs are primarily active from mid-June to mid-September. Once they find a suitable spot to settle, they begin to form new colonies. Adults have reddish to purple bodies and are completely covered with woolly white wax. Overwintering aerial colonies do not produce the woolly white wax and are therefore more difficult to detect than are summer colonies.

Infestations are spread from tree to tree by wind and birds. Woolly apple aphids may also be brought into the orchard on nursery stock.

Aerial colony of woolly apple aphids
Aerial colony of woolly apple aphids

Root colonies cause swollen, root galls
Root colonies cause swollen, root galls


Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright © 2014 The Regents of the University of California. All rights reserved.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See our Home page, or in the U.S., contact your local Cooperative Extension office for assistance.

Agriculture and Natural Resources, University of California

Accessibility   /PMG/GARDEN/FRUIT/PESTS/LIFECYCLE/lcwoolapaph.html revised: January 8, 2014. Contact webmaster.