Cottonwood Poplar Petiole Gall Aphid: Life Cycle and Organic Management

Identification

Grey bugs in pod-like galls on leaf petioles = Poplar Petiole Gall Aphid (Pemphigus populitransversus).

Life Cycle

1. Eggs overwinter on leafless twigs
2. Spring hatch → nymphs feed on petioles → galls form
3. Aphids secrete white wax inside galls
4. 2 weeks → winged females → migrate to mustard family plants
5. Fall → return to cottonwoods → lay overwintering eggs

Impact

• Premature leaf drop late summer
• Not serious health threat
• Populations vary yearly

Organic Management

1. Rake and destroy ALL galled leaves - reduces next year's population
2. Systemic insecticide (Bayer Advanced) if needed - soil applied early spring
3. Generally, no control necessary