Sawflies

Sawfly larvae resemble butterfly or moth caterpillars but typically have more pairs of fleshy prolegs along the abdomen and often curl into a distinctive "S" or coiled shape when disturbed. Adults are non-stinging wasp-like insects rarely noticed causing damage themselves.

Signs of infestation include skeletonised or ribbon-like feeding patterns on leaves, scarring or tunnelling on developing fruit, and groups of larvae feeding together on affected foliage.

Female sawflies use their saw-like ovipositor to insert eggs into leaf tissue, developing fruit, or stems, depending on species. Larvae feed for several weeks before many species drop to the soil to pupate, overwintering there until adults emerge the following season.

The number of generations per year and the timing of larval activity vary by species and region, often tracking crop phenology such as bloom or pod development.

Larval feeding can defoliate trees and shrubs, scar or tunnel into developing fruit, or damage stems and pods in field crops, with economic impact depending heavily on crop stage and species involved.

Host crops include apple, pear, and oilseed rape, among other tree fruit and field crops attacked by particular sawfly species.

Scouting for larvae and characteristic feeding damage during bloom and early fruit or pod development, alongside degree-day models where available, helps time monitoring to periods of greatest risk.

Sawfly management fits within integrated pest management, combining several tactics rather than relying on any single approach.

• Conserve parasitoid wasps, birds, and ground beetles
• Time monitoring to bloom or pod-development stages when larvae are most likely to establish
• Consider tillage or soil disturbance where it disrupts soil-overwintering pupae without harming beneficial organisms
• Monitor and use local thresholds to guide any intervention