Pear sawfly

The pear sawfly (Caliroa cerasi), also known as the cherry slug, belongs to the family Tenthredinidae. Despite its common name, it is a significant pest of various Rosaceae species, capable of causing widespread defoliation in commercial orchards and home gardens alike.

The insect primarily targets stone fruits and pome fruits. Favored host plants include cherry, plum, pear, hawthorn, and mountain ash. The damage is most visible during the summer months when the larvae feed actively on the foliage of these trees.

The life cycle typically consists of two generations per year. The larvae overwinter in soil cocoons. In spring, adults emerge to lay eggs inside the leaf tissue. The larvae emerge after about two weeks and are distinguished by their dark, slimy, slug-like appearance, which serves as a defense mechanism against predators.

The damage is characterized by skeletonization of the leaves. The larvae consume the upper leaf surface, leaving behind only the veins and the lower epidermis, which turns brown and eventually dries out. Severe infestations result in a scorched appearance of the canopy, leading to premature leaf drop and weakened tree vigor.

Management strategies focus on reducing the population before significant damage occurs. Key control measures include:

• Cultivating the soil around the base of trees to expose overwintering cocoons
• Monitoring the canopy for the presence of slimy larvae in late spring
• Applying contact or systemic insecticides during peak activity
• Utilizing insecticidal soaps or horticultural oils for organic management