Thrips (or thunder flies due to their association with increased aerial activity in sultry humid conditions) are small insects up to 2 mm long with cylindrical brownish/ yellow bodies and 2 pairs of narrow wings edged with long fine hairs. The yellow coloured larvae are similar in appearance to adults but without wings.
The larvae feed on the plant sap through their piercing and sucking mouthparts which damage the plant cells of the leaves and the developing pods giving the characteristic mottled, ‘silvery’ and distorted appearance.
Eggs are laid in the pea flowers and hatch after 7-10 days. The young larvae feed on the flowers, leaves and pods for 2-3 weeks before dropping to the soil to pupate. The adults emerge in suitable conditions in May to June the following year and fly up into the growing crop. There is 1 generation per year.
Damage done to the developing pods is rarely of economic importance and insecticides are not generally justified although cosmetic damage to the edible podded pea market can be of greater concern. Activity peaks in hot dry conditions. Insecticides applied to control other insect pests of peas will also reduce damage caused by pea thrips.
Pea thrips adult on pea flower
Pea thrips larva on a pea leaf
Pea thrips damage