Lettuce aphid on lettuce and romaine
Lettuce aphid feeds in the heart, on the youngest leaves, so a head can look clean from outside and be infested at the core. In organic romaine on California's Central Coast, hoverfly larvae made up 85% or more of the predators in most trials, and were the only predators consistently found in romaine that was infested early and largely aphid-free by harvest. Where spinosad suppressed them, the romaine was unmarketable. Syrphid flies cannot be bought, so the flowers are what bring them in.
At a glance
- Damage
- Aphids packed into the heart of the head; contaminated, unsaleable lettuce
- Type
- Sap feeding
- Settings
- Field, Garden
- Threshold
- None published for lettuce aphid; UC IPM's 20 aphids per plant is for green peach and potato aphid
- Ally
- Syrphidae
- Rate
- Wild — nothing to release. Intercrop with sweet alyssum, coriander, baby's breath or Persian clover (UC IPM; skip alyssum where Bagrada bug is building)
How to confirm it
Pull the head apart. Green, orange or pink aphids tucked among the youngest leaves in the heart, with black markings at the joints of the legs and antennae, are lettuce aphid. Green peach aphid starts on the lower leaves instead.
Identification, lifecycle, degree days and every control option are on the full Lettuce aphid profile. Not sure it is this pest? Answer four questions about the damage.