European Sawfly and pine trees

The European Sawfly is an introduced pest that primarily attacks pine trees. It gets its unusual name from saw-like structures on its abdomen that the female uses to cut a slit into pine needles where she deposits her eggs.

Sawfly larvae feed on mature needles at the ends of branches

The eggs hatch late April through early May and the newly hatched larvae feed on the previous year’s needle growth at the ends of branches. Many unsuspecting people have been shocked when they first discover sawfly larvae because they group together in clusters and all of them rise up in unison end when startled.

Large pine trees are minimally affected by sawfly larvae and mostly go unnoticed. Small pine trees and mugo pine shrubs can be defoliated after repeated years of attack. Often the branches of the small tree or shrub will be bare with only the new growth shoots remaining at the tips. Sawfly larvae can be treated with contact insecticides when they are active in spring.

Here’s what we can do

Shadywood Tree Experts can help maintain your pines with proper pest identification and insecticide spray applications. When you sign up for plant health care from Shadywood, we administer the recommended protocols for disease prevention control to keep your trees and shrubs healthy. With each visit, our arborists assess trees and shrubs for overall health.

These sawfly larvae are reaching maturity and they will pupate into flies later in the summer

Additional things you can do to maintain the health of your Pine

Water large trees regularly using a hose or small sprinkler for at least an hour once every one to two weeks if there has not been adequate rain. Small shrubs can be watered for a few minutes. Avoid spraying needles directly when watering as wet needles can promote fungal diseases. Mulch root systems when possible, using natural wood chips to condition and improve the soil and to conserve soil moisture. If you see anything that doesn’t look right, have your trees inspected by one of Shadywood Tree Experts International Society of Arboriculture Certified Arborists.