Pest description and crop damage The California pear sawfly should not be confused with the pear sawfly or pear slug (Caliroa cerasi), which is also a sawfly, but whose larvae are slug-like. The larvae of the California pear sawfly look like caterpillars. They are bright green and about 0.5 inch long. The larvae eat round holes in leaves and with extensive feeding only the midribs will remain. Although they do not directly attack fruit, they can defoliate a tree, or an orchard, in a matter of weeks. They are considered to be a minor pest of pear.
Biology and life history The insect overwinters as a pupa in the soil. In early spring the sawflies emerge and after mating the females lay eggs around the edges of leaves. Larvae emerge around petal fall and commence feeding. Their feeding leaves characteristic circular holes in the leaves, and also in the edges of the leaves in a pattern that resembles leafcutter bees. They continue feeding into May, at which time they fall to the soil to pupate and overwinter. There is only one generation per year.
Pest monitoring Observe trees for characteristic feeding damage early in the year.
Management-chemical control: HOME USE
- azadirachtin (neem extract)-Products containing neem extract may be phytotoxic to some pear cultivars. Some formulations are OMRI-listed for organic use.
- bifenthrin-Highly toxic to bees.
- carbaryl-Highly toxic to bees.
- gamma-cyhalothrin-Highly toxic to bees.
- imidacloprid-Highly toxic to bees. Soil drenches may have residual activity in woody plants lasting for 12 or more months. If short-term management is the goal, consider other approaches.
- insecticidal soap-Some formulations are OMRI-listed for organic use.
- lambda-cyhalothrin-Highly toxic to bees.
- pyrethrins-Highly toxic to bees. Some formulations are OMRI-listed for organic use.
- spinosadSome formulations are OMRI-listed for organic use.
- zeta-cypermethrin-Highly toxic to bees.
Management-chemical control: COMMERCIAL USE
Usually controlled by regular spray programs but if high populations occur in organic pear orchards, application of spinosad (Entrust) has been found to provide control.