Lettuce Aphid

family: aphididae
species: nasonovia ribisnigri
common names: lettuce aphid
hosts: lettuce
notes:

THE FOLLOWING (UNTIL OTHERWISE NOTED) IS FROM: GERBER, H.S. 1983.
MAJOR INSECT AND ALLIED PESTS OF VEGETABLES IN BRITISH COLUMBIA.
MINISTRY OF AGRICULTURE AND FOOD.

Lettuce Aphid

Nasonovia ribisnigri (Mosley)

Economic damage to lettuce first occurred in the Cloverdale lettuce growing area in 1981 and was more extensive in 1982. The aphid has been found throughout the Fraser Valley and on Vancouver Island.

Vegetables Attacked:

Lettuce

Injury:

Large numbers of aphids may stunt young plants. Lettuce heads with aphids in them are not saleable.

Insect:

Lettuce aphids can be winged or wingless and are usually olive-green mottled with dark brown, although pink ones are most common within the heads. Colonies are found on the inside surfaces of wrapper leaves and inside heads.

Life History:

The lettuce aphid overwinters as eggs on black currant and gooseberry bushes, and possibly on other plants. Eggs hatch in late March and April. Winged aphids migrate into lettuce fields in May and June. Many generations of winged and wingless aphids are completed on lettuce throughout the summer when winged aphids fly to other lettuce fields and start new colonies. In October, winged aphids return to their winter host plants where they mate and lay eggs.

Monitoring:

Fields should be checked for aphids on a twice weekly basis. To do this, walk down outside beds and up the centre bed examining four heads at equal intervals within each bed. Examining means stripping the heads and inspecting each leaf for aphids. If a single aphid is found, a spray program should be followed.

Control:

See the current Vegetable Production Guide for Commercial Growers. Ploughing under infested plantings will prevent further spread of aphids. For maximum control, ploughed plant material should be thoroughly covered with soil.