Q What is pea moth?
A It is a drab, small moth (Cydonia nigricana) that lays its eggs on pea flowers. The resulting caterpillars tunnel into the pod, and feed on the peas. You don't even know it's there until you shell them.
Caption: Pea moth is not pleasant to find when shelling peas
Q Which plants does pea moth affect?
A Pea-family plants. Peas are attacked, but runner, French and broad beans seem immune. Among ornamentals, sweet peas are at risk, but not lupins.
Q How do I recognise pea moth?
A The moth is small (15mm) and grey-brown, with white wing tips. It is usually hard to spot. Sometimes it's seen on pea plants in summer, especially around mid-July. The most reliable way to spot it is to use a pheromone trap. These use attractants normally given off by male moths, to lure females to sticky traps. The eggs are tiny green scales. They're hard to spot; look for them around flowers on leaves and stipules. You’ll need a hand lens.
Q What damage does pea moth do?
A Pale-yellow caterpillars 9mm long with black heads and brown dots feed on peas inside the pods. Usually only a few peas in each pod are affected as there are rarely more than two caterpillars per pod, and each caterpillar needs only one or two peas to feed on. By sorting, you can still save much of the crop.
Q When can I expect pea-moth attacks?
A The moths spend the winter in cocoons in soil where peas were grown last year and in nearby rough ground and rubbish heaps. They come out in late May and June and are active all summer. During June and July they lay their flattened, tiny eggs in twos and threes on leaves and around flowers. These hatch in about eight days. The tiny caterpillars make their way to the pods and tunnel inside. It takes about three weeks for them to mature, after which they cut their way out and fall to the ground. Before pupating, they burrow into the soil and form cocoons, in which to spend the winter. In spring they leave the cocoons and come closer to the surface, where they weave other cocoons in which to pupate. They leave as adult moths.
Q Could I mistake pea moth for anything else?
A Maggots found in emerging peas in late spring are probably those of the bean-seed fly. This pest doesn't attack pods. Other pea troubles are pea thrips (thunder flies), which attack the pods, giving them a silvery sheen.
Q Can pea moth be sprayed?
A Once the caterpillar is inside the pod, sprays are ineffective. There are no preventative sprays available to gardeners. Too early and their effect will have worn off before the moth arrives, too late and the caterpillar will be safe inside the pod.
Q Can pea moth be avoided?
A When peas flower before mid-June they escape attack, as pods are past the vulnerable stage by the time the moth is flying. Sowing in October and November under cloches, or in pots indoors in January and February, outdoors until mid-March, will avoid the moth. You’ll need to use a fast-growing early variety such as 'Feltham First', 'Meteor' or 'Douce Provence'. Early sowings outdoors can rot in the ground. Cover the sowings with fleece to help survival. Sowings after the middle of May will be in flower too late for the moth to infest them. Since these late peas can get mildew, look for a mildew-resistant variety.
Q What should organic growers do against pea moth?
A Covering pea crops with insect-proof mesh when they are in flower from mid-June onwards will protect the pods. It will also keep birds off – birds, especially jays, can destroy many pods.
Q Are mangetout and snap peas affected by pea moth?
A These are eaten when the seeds are very small, which is usually before the caterpillars have damaged the edible parts.
Q What should I do with plants by pea moth?
A The plants can be composted, as the moths enter the soil after leaving the pods. Dig over the pea patch early in the autumn to let birds and other predators eat as many cocoons as possible.
Suppliers of insect-proof mesh and fleece
Ferndale Lodge 0844 314 0043 ferndale-lodge.co.uk
Gardening Naturally 0845 680 0296 gardening-naturally.com
Harrod Horticultural 0845 402 5300 harrodhorticultural.com
The Organic Gardening Catalogue 01932 253666 organiccatalogue.com