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

• 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

If pea moth has been a problem in previous years consider control options before sowing peas.

When choosing control options you can minimise harm to non-target animals by starting with the methods in the non-pesticide control section. If this is not sufficient to reduce the damage to acceptable levels then you may choose to use pesticides, although in the case of this moth they can be avoided by using insect proof mesh.

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 be affected.

Pesticide control

The RHS believes that avoiding pests, diseases and weeds by good practice in cultivation methods, cultivar selection, garden hygiene and encouraging or introducing natural enemies, should be the first line of control. If chemical controls are used, they should be used only in a minimal and highly targeted manner.

Pesticide control can be avoided by using insect-proof mesh. Whilst there are some insecticides labelled for use on peas (for example the synthetic pyrethroids deltamethrin, e.g. Sprayday Greenfly Killer or lambda-cyhalothrin e.g. Westland Resolva Bug Killer) adult pea moth is active when peas are in flower and plants in flower should not be sprayed due to the danger to pollinating insects.

Follow label instructions when using pesticides. On edible plants make sure the food plant is listed on the label and follow instructions on maximum number of applications, spray interval and harvest interval. Inclusion of a pesticide product does not indicate a recommendation or endorsement by RHS Gardening Advice. It is a list of products currently available to the home gardener.

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Pesticides for gardeners (pdf document)

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.