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Pear Slug (Cherry Slug or Pear Sawfly)

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.