Biology and management of the pea moth

Pea moths are one of the most damaging UK pea pests. Larvae feed on peas inside the pod leading to contamination issues and reductions in quality. Attacks are most frequent in intensive pea-growing areas.

• Any pea crop in flower or in pod in June or July can be attacked
• Risk is greater where there has been severe damage in previous crops. Control may only be justifiable in these cases
• Early maturing and early or late-sown peas may miss the moth flight period, reducing risk

Scientific name: Cydia nigricana

Moths are dull grey-brown with white and black markings on the leading edge of each forewing. They are approximately 6 mm long, with a 15 mm wingspan.

Eggs are small and flattened.

Caterpillars are pale yellow with a black head and legs. When mature, they are around 10 mm long. They have a brown ring on the prothorax, with eight brown dots on the following segments.

Oct–Mar: Overwinter in cocoon about 10 cm below ground.

Apr–May: Caterpillar emerges to form a second cocoon at soil surface. Pupation occurs upon leaving this cocoon.

May–Aug: Moths emerge in late May/early June and lay eggs singly or in small groups on leaves and stipules of pea plants from early June until mid-August.

Jun–Aug: Hatched caterpillars enter young pods to feed. Pea pods rarely contain more than two caterpillars each. Damaged pods may appear yellow and ripen early.

Jul–Sep: Mature caterpillars bite their way out of their pod and descend to the soil to form a cocoon underground.

Non-chemical control

Large pea moth populations can develop where pea crops remain in the field to full maturity. Therefore, combining pea areas are likely to be a reservoir. Plough in unharvested green peas before larvae leave dried pods. Early maturing and early or late-sown peas may miss the moth flight period, so may be unaffected. Pea moth is attacked by four species of parasitic wasp and a pathogenic fungus.

Monitoring

Use pheromone traps to catch males. Place traps in crops by mid-May. Examine at 2-day intervals. Use monitoring results and a computer model (use daily minimum and maximum temperatures) to predict egg development. Use the information to target sprays at newly hatched larvae before they enter pods. See pgro.org for the latest pea moth alerts.

Thresholds

Dry harvested peas for human consumption: Ten or more moths caught in traps on two consecutive occasions.

Vining peas: Use traps to determine if moths are present. Growers should be guided by the factory fields-person: even very small infestations can lead to rejection.

Insecticide resistance

None known.