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How to identify it
- Wingless adults are pale green to yellow and about 2 mm long.[1][2]
- Adults and nymphs carry small knobbed (clubbed) hairs on the back and fine crosswise lines across the abdomen. A hand lens shows them easily, and no other aphid on strawberry has them.[1][2]
- Winged adults are pale green with black markings on the head, thorax and abdomen.[2]
- In winter look in the crown, where adults and nymphs shelter, and for black eggs on the undersides of older leaves.[2]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Melon aphid | Small and globular, yellowish green to greenish black, without the knobbed hairs. It is often the first aphid to move into strawberry fields and the hardest to control with insecticides.[1] |
| Green peach aphid | Green to greenish yellow and more streamlined; winged adults have a black spot on top of the abdomen.[1] |
| Potato aphid | Much larger, with pink and green forms and long legs that give it a spiderlike look.[1] |
Where it lives
It is one of the aphids that infest strawberries in California, and it is also a strawberry pest in the Pacific Northwest.[1][2]
Biology and life cycle
In the Pacific Northwest it overwinters as adults or nymphs in the crown or as black eggs on older leaves. Winged adults appear in May and spread within and between fields.[2]
Numbers peak in June, and in some years there is a second peak in September or October. Several overlapping generations develop each summer.[2]
In Central and Southern California strawberry fields, aphid numbers usually peak in late March and fall to insignificant levels in May and June; in high-elevation nurseries they peak in mid- to late summer.[1]
Aphids in strawberries are attacked by many parasites and by predators such as lady beetles and the larvae of syrphid flies and green lacewings.[1][2]
Damage and signs
- Feeding by this aphid generally does not injure strawberry plants directly.[2]
- The real risk is virus disease. Aphids spread several strawberry viruses that can cause serious losses in plantings left in the ground for several years and are a major concern for nurseries, though less so in fields replanted every year.[1][2]
- In California fields aphids rarely reach damaging levels, but when they do build up their sticky honeydew grows sooty mold and glues shed white aphid skins to the berries, which can make fruit unmarketable fresh.[1]
Health risk
It is a plant pest; neither source describes any risk to people or pets.[1][2]
Control
Prevention
The PNW handbook calls virus-resistant plants probably the most effective control.[2]
Avoid heavy nitrogen fertilizer, since aphid numbers run higher on plants that get too much. Floating row covers can cut aphid numbers, but they won't help plants that are already infested.[2][1]
Traps and physical control
Home gardeners can wash aphids off plants with a strong stream of water. Check the undersides of leaves and the crowns in early spring and again after harvest and in early fall.[2]
Biological control
Compare the number of parasitized aphids (mummies) with healthy ones, and count predators such as lady beetles before treating. If natural enemies are gaining, avoid sprays that would disrupt them; controlling dust also helps parasites and predators work.[2][1]
Pesticides
For home plantings the PNW handbook does not suggest chemical control, because sprays have not stopped virus spread and aphid feeding has not warranted treatment. Commercial growers and nurseries treat to slow virus spread, combined with certified plants, removing abnormal plants and isolating new fields; insecticidal soap reduces aphid numbers with little harm to natural enemies.[2][1]
Common questions
- How can I tell strawberry aphids from other aphids on my strawberries?
- Use a hand lens: strawberry aphids have knobbed hairs on the back and fine crosswise lines on the abdomen, which no other aphid on strawberries has.[1][2]
- Do I need to spray strawberry aphids in my garden?
- Usually not. They seldom injure plants directly, and the PNW handbook does not suggest chemical control for home plantings; a strong spray of water knocks them off.[2]
- Why do growers worry about such a small aphid?
- Because it can transmit strawberry virus diseases, which matter most in nurseries and in plantings kept for several years.[2][1]
Sources
- University of California Statewide IPM Program, “Strawberry Pest Management Guidelines: Aphids.” ipm.ucanr.edu/agriculture/strawberry/aphids/ (accessed 2026-11-09)
- Pacific Northwest Pest Management Handbooks (Oregon State University, Washington State University and University of Idaho Extension), “Strawberry-Aphid (PNW Insect Management Handbook, small fruit).” pnwhandbooks.org/insect/small-fruit/strawberry/strawberry-aphid (accessed 2026-11-09)
- iNaturalist, “Chaetosiphon fragaefolii taxon page (order and family).” www.inaturalist.org/taxa/407903 (accessed 2026-11-09)