Pea moth

Pea moth caterpillars feed inside pea pods but the damage is often only spotted at harvest. Consequently, the pods need to be shelled with care to avoid contamination.

Pea moth

Quick facts

Common name Pea moth
Latin name Cydia nigricana
Plants affected Garden peas
Main symptoms Small creamy white caterpillars eat the peas inside the pods
Caused by Caterpillars of a small moth
Timing Late June-August

What is pea moth?

Pea moth is a small (15mm wingspan), grey-brown moth whose larvae (caterpillars) feed in the pods of garden peas.

Symptoms

  • When pea pods are opened for shelling, one or more creamy white caterpillars, up to 14 mm long, with dark dots on the body may be found eating into the peas
  • There are piles of caterpillar excrement (frass) near the damaged peas

Control

Non-pesticide control

Peas can be grown under horticultural fleece, insect-proof mesh, to prevent female moths laying eggs on the plants. Peas are self-pollinating and so excluding bees and other pollinators with fleece will not affect the crop.

Quick-maturing cultivars that are sown early or late and which flower outside of the egg laying period of the moth (June and July) should remain un-infested. Similarly mange-tout types of pea, where the pods are eaten before the seeds develop, should not become infested.

Pesticide control

Chemical control can be avoided by the use of insect-proof mesh and is difficult as plants in flower should not be sprayed due to the danger to pollinating insects. Advice in the past has been to spray the plants with an approved pesticide once at the beginning of flowering and again two weeks later. Alternatively spraying with an insecticide when most of the flowers have gone over and pods are beginning to form may give some control, suitable insecticides include the synthetic pyrethroids deltamethrin (e.g. Sprayday Greenfly Killer) or lambda-cyhalothrin (e.g. Westland Resolva Bug Killer). The label instructions for the crop must be followed.

Inclusion of a pesticide product does not indicate a recommendation or endorsement by RHS Garden Advice. It is a list of products currently available to the home gardener

Download

Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)

Biology

Adult pea moths emerge in June-July, when the females seek out pea plants on which they lay their eggs. They are attracted to pea plants that are in flower.

After hatching, the caterpillars bore into the developing pea pods and begin feeding on the seeds. When fully fed in mid- to late summer, the caterpillars leave the pods and go into the soil to pupate.


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