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