Syrphidae
Hoverflies- Kind
- Wild — attract it
- Best for
- Main predator in field lettuce; attract with flowers
Pest
Lettuce aphid
Nasonovia ribisnigri
The short answer
An aphid of lettuce that lives in the heart of the plant, on the youngest leaves, rather than on the outer leaves where other aphids start. It comes in green, orange and pink forms, with black markings at the leg and antenna joints. The harm is contamination: aphids inside the head make it unsaleable, and they are hard to see and hard to hit with sprays. In Europe it has developed resistance to some insecticides and has broken the resistance bred into lettuce varieties.
hero macro · lettuce aphids among the heart leaves
Wingless Nasonovia ribisnigri in the heart of a lettuce head. Photo: pending.
Identification
Wingless adults are 1.3–2.7 mm long and come in green, orange and pink forms. Both wingless and winged adults have black markings on the joints of the legs and antennae. Some wingless forms also have black markings on the back of the abdomen. Winged forms are browner, with a conspicuous pattern of black markings on the abdomen. The cornicles are pale with dark tips.
Where it sits is the best clue. In head lettuce it is found almost exclusively in the heart, on the youngest leaves. It tends to disperse through the plant rather than forming tight colonies as green peach aphid does. Green peach aphid, the other common lettuce aphid, starts on the lower leaves and has bumps at the base of the antennae that point strongly towards each other; lettuce aphid's do not.
Easily confused with
- Green peach aphidAlso a pestGreen peach aphid has bumps at the base of the antennae that grow strongly towards each other, and its infestations begin on the lower leaves. Lettuce aphid's bumps do not converge strongly, and it sits in the heart.
- Potato aphidAlso a pestAlso pink or green, but larger, with longer cornicles and tail. Potato aphids cluster closely in colonies, whereas lettuce aphid tends to disperse through the heart.
- Lettuce root aphidAlso a pestLives on the roots in colonies covered in white powdery wax, and the plant wilts in the heat of the day. Lettuce aphid is on the leaves, in the heart.
- Aphelinus mummiesBeneficial — leave itA black, elongated aphid body that no longer moves is a mummy with an Aphelinus wasp developing inside. Leave it on the plant.
Damage symptoms
Lettuce aphid feeds deep inside the plant, on the younger leaves towards the centre, so the damage is mostly contamination rather than visible feeding. UC IPM notes that it does not appear to be a significant virus vector. Because it hides and multiplies quickly, infestations are easy to miss until the heads are harvested.
- Aphids among the youngest leaves in the heart, often with none on the outer leaves
- Green, orange or pink aphids with black markings at the leg and antenna joints
- Heads that look clean from outside but are infested at the core
- Browner winged aphids, with black markings on the abdomen, scattered through the plant
Lifecycle & degree days
In Europe the aphid alternates between hosts. Eggs overwinter on currant and gooseberry bushes, and winged forms fly to lettuce and related plants in May and June. Generations follow on lettuce until autumn, when winged forms return to the bushes to lay eggs. In California there is no need for currants: UC IPM reports that it appears to pass the winter as nymphs and adults on lettuce, radicchio, Nicotiana and some other composites. Lettuce with the Nr resistance gene gave complete resistance until virulent aphids, known as biotype Nr:1, appeared in Europe in the 2000s. Accounts of when Nr arrived differ: 1982 in one study, the 1980s in another, and a first resistant cultivar released in 1996 in a third.
- Winter (Europe)
- Eggs on currant and gooseberry
- Winter (California)
- Nymphs and adults on lettuce, radicchio
- Moves to lettuce
- May–June (Europe)
- Resistance-breaking biotype
- Nr:1, in Europe from the 2000s
J
F
M
A
M
J
J
A
S
O
N
D
Host crops
Lettuce is the crop that matters. Radicchio and chicory, Nicotiana and several wild composites such as nipplewort and hawkweed also carry it. In Europe its winter hosts are currant and gooseberry bushes. Lettuce varieties carrying the Nr gene were fully resistant in trials, with no aphids surviving a week on them, but the Nr:1 biotype, first reported in Europe in the 2000s, feeds on resistant and susceptible lettuce alike.
Monitoring & action thresholds
Action threshold
None published
UC IPM gives no treatment threshold for lettuce aphid. Its figure of 20 aphids per plant before heading applies to green peach and potato aphid, not to lettuce aphid. With lettuce aphid, the practical point is timing: UC IPM warns that monitoring takes care not to miss early infestations hidden in the plant, because once the head closes over them they are out of reach.
Open up a sample of plants and look into the heart, not just at the outer leaves. UC IPM advises care so as not to miss early infestations hidden within the lettuce. Look for the black leg joints to separate it from green peach aphid, and count hoverfly eggs and larvae as you go: they are the main natural control in the field.
Beneficial
Biological control
Hoverfly larvae are the lettuce aphid's main natural enemy. In organic romaine on California's Central Coast they made up 85% or more of the predators in most trials, and romaine sprayed with spinosad, which suppresses them, was unmarketable at harvest while unsprayed romaine was marketable. Toxomerus marginatus was the commonest species, at 39% of larvae. Green lacewing larvae also feed on it, and UC IPM rates lady beetles and parasitoids as minor. In a Danish laboratory test, Aphelinus abdominalis parasitised 39% of lettuce aphids in a day, while Aphidius colemani, the usual greenhouse aphid wasp, parasitised none in a 6-hour test.
Chrysoperla carnea
Green lacewing- Rate
- 2–20 /m² per release, weekly
- Temp
- 20–28 °C best; works above a 12 °C average
- Best for
- Larvae favoured lettuce aphid over thrips in lab tests; UC IPM names lacewings as field predators
Aphelinus abdominalis
Aphid parasitoid wasp- Rate
- 0.25–4 /m² per release, repeated
- Temp
- 15–35 °C (59–95 °F); outperforms Aphidius above 28 °C
- Best for
- Parasitised 30–54% in lab tests; field use unproven
Cultural controls
Resistant varieties and natural enemies carry most of the control. The aphid's hiding place makes contact sprays a poor fit.
- Grow lettuce varieties with the Nr resistance gene, but expect the Nr:1 biotype to overcome them where it is present
- Plant sweet alyssum, coriander, baby's breath or Persian clover among the lettuce to feed adult hoverflies (skip alyssum where Bagrada bug is building)
- Avoid spinosad and broad-spectrum sprays that kill hoverfly larvae
- Check the heart of young plants before the heads close
- In Europe, keep lettuce away from currant and gooseberry bushes, where the aphid overwinters
Chemical, last resort
It hides in the heart, so contact sprays miss it, and it is resistant to some insecticides in Europe. Imidacloprid and dimethoate must not be applied or drift onto flowering plants (bees)Check any product before it goes on. Open the compatibility matrix →
- FlonicamidREI 12 h
- SpirotetramatREI 24 h
- Imidacloprid (soil)REI 12 h
- Dimethoate (commercial only)REI 48 h
Rating: the effect on this pest's natural enemies if a spray hits them or they feed on treated plants. REI is the re-entry interval on farm and greenhouse labels; home labels usually give none, so follow the label.
Sources
UC IPM Pest Management Guidelines: Lettuce — Lettuce Aphid (Natwick, Joseph & Dara, 2017)
UC IPM Lettuce PMG: Green Peach and Potato Aphids; Lettuce Root Aphid (2017)
UC IPM, Relative Toxicities of Insecticides Used in Lettuce to Natural Enemies (2017)
Smith & Chaney, Syrphid predators of N. ribisnigri in organic lettuce, J. Econ. Entomol. 2007
Smith, Chaney & Bensen, Syrphid larvae suppressing aphids in organic lettuce, J. Econ. Entomol. 2008
ten Broeke et al., Two biotypes of the currant-lettuce aphid, Bull. Entomol. Res. 2013
Liu & McCreight, N. ribisnigri on susceptible and resistant lettuce, J. Econ. Entomol. 2006
Garrett et al., N. ribisnigri genome and resistance breaking, Insect Mol. Biol. 2024
Rufingier et al., Insecticide resistance in N. ribisnigri from France, Insect Biochem. Mol. Biol. 1999
Shrestha, Skovgård & Enkegaard, Aphelinus and Aphidius on lettuce aphids, Environ. Entomol. 2014
Shrestha & Enkegaard, Chrysoperla carnea preference for lettuce aphid, J. Insect Sci. 2013
Shrestha et al., Aphelinus abdominalis on lettuce and potato aphids, PLoS One 2017
Del Pozo-Valdivia et al., Drone-released lacewings in organic lettuce, J. Econ. Entomol. 2021
InfluentialPoints, Nasonovia ribisnigri (currant-lettuce aphid) species account
Page status
Drafted from the sources below, then checked claim by claim against those sources on 23 September 2026.
Suggest a correction →Lettuce aphid by crop
The same pest behaves differently on different hosts. Each page below gives the host-specific control, rate and threshold.