Pear Slug (Cherry Slug or Pear Sawfly)
Hosts: cherry, pear
Biology: Overwinters as a sawfly pupa in the soil. Adults lay eggs on leaves in mid summer. The larvae have a slug-like appearance and feed on the upper surface of the leaf epidermis creating "windowpanes."
Symptoms/Damage: They cause a skeletonizing injury where membranous “windows” of leaf tissue remain in between leaf veins. Leaf feeding injury can proceed rapidly when populations are high.
Monitoring: Watch for sawfly larvae starting in mid to late July.
Treatment Threshold: No threshold determined.
Degree Day Model: None
Management Considerations: The larvae are often suppressed by insecticides applied for other pests. Trees can tolerate low populations.