Hymenoptera

These pests affect a wide range of agricultural and horticultural plants. Major crops at risk include apples, pears, cherries, gooseberries, and currants. Furthermore, certain species, such as the spruce or pine sawfly, cause significant damage to forestry and ornamental conifers by consuming needles, which can lead to tree stress and mortality if infestations are severe.

The life cycle typically includes egg, larval, pupal, and adult stages. Most sawfly species overwinter as prepupae in cocoons within the soil. Adult emergence is synchronized with the phenology of their host plants in the spring. Mated females then lay eggs inside the leaf tissue or buds, ensuring that larvae emerge precisely when the plant material is most succulent and vulnerable.

Sawfly larvae, often referred to as "false caterpillars," look similar to butterfly caterpillars but have more prolegs. They exhibit diverse feeding habits: some are leaf miners, others are skeletonizers, and some are defoliators that can strip a branch entirely in days. Their presence is often detected by the specific pattern of damage or the accumulation of frass on leaves.

Integrated pest management (IPM) is the most effective approach for control. Cultural controls, such as soil cultivation to disrupt pupation sites and manual removal of infested shoots, should be the first line of defense. Chemical control using selective insecticides is recommended only when monitoring confirms that larval populations have reached the economic threshold.

• Monitor adult flight using yellow sticky traps in early spring.
• Cultivate soil under host plants to expose overwintering cocoons.
• Hand-pick larvae from small shrubs or garden plants.
• Encourage natural predators such as parasitic wasps and predatory beetles.
• Apply targeted systemic insecticides during the peak of larval hatching.