Field Identification
A blue-green to olive aphid that colonizes lettuce heads, endive, escarole, and related composites—often deep inside wrapper leaves where washing misses it. Feeding causes stunting, contamination, and rejection at market; it tolerates cool weather better than many aphids, so it dominates in spring and fall tunnels and coastal fields. Worldwide distribution includes intensive production zones across the United States, Mexico, Central America, and Andean cool highlands wherever lettuce ships year-round—roughly zones 3–11 in field contexts, with greenhouse pressure beyond.
Adults and nymphs are somewhat tuberculate and waxy, often hiding near the meristem and heart. Cornicles are short and dark; antennae are long relative to green peach aphid. Winged forms disperse between blocks—sticky cards in tunnels spike before colonies explode inward.
How to Deal With It
Organic Control Methods
Insecticidal soap or horticultural oil with high-pressure rinse opens rosettes enough for contact; repeat every 2–3 days while migrating alates arrive. Neem and azadirachtin reduce reproduction on outer leaves. Avoid spraying open lettuce flowers if bolting plants are near insectary rows; dawn or dusk applications reduce bee overlap on adjacent crops.
Aphidius spp., Aphelinus spp., and generalist predators such as syrphid larvae and minute pirate bugs attack lettuce aphid in open heads if outer leaves are not stripped too aggressively. Banker plants in greenhouses support parasitoids when compatible with food safety plans.
Choose resistant cultivars where seed is available for your market class. Increase between-row airflow in tunnels to reduce humid pockets aphids love. Remove cull piles and bolting lettuce at field edges that host winged stages.
For small plantings, submerge harvested heads briefly in cold water with gentle agitation—this is post-harvest quality control, not a field fix. Blowers and leaf separators in pack sheds remove some aphids after careful wash line design.
Scout hearts twice weekly by peeling two wrapper leaves on sample plants. Blue sticky traps at tunnel doors track incoming flights. Rotate tunnel houses with a host-free break when possible to starve residual populations.
Let Nature Handle It
Natural Enemies
- Aphidius spp. (Braconidae)
- Aphelinus spp.
- Syrphid Fly Larvae (Syrphidae)
- Minute Pirate Bugs (Orius spp.)
Threat Map