Elm sawfly

The elm sawfly (Trichiocampus ulmi) is a member of the order Hymenoptera and the family Tenthredinidae. This insect is specifically known for its ability to cause significant defoliation in elm species (Ulmus), posing a threat to both urban street trees and forest plantations.

The host range is primarily focused on various species of the elm genus. The larvae are specialized leaf-feeders that rely exclusively on the foliage of these trees to complete their development. Severe infestations can lead to partial or complete stripping of the tree canopy, which weakens the tree's health over time.

Regarding its biology, the insect typically overwinters as a prepupa within a cocoon located in the soil or under leaf litter. In the spring, adult sawflies emerge, mate, and deposit eggs into the tissue of the developing leaves. The larvae hatch and begin feeding immediately, going through several instars of growth.

The damage caused by Trichiocampus ulmi is characterized by leaf skeletonization. Younger larvae often feed in groups, consuming the softer leaf tissues between the veins. As they grow larger, they consume entire leaf blades, leaving only the primary veins behind. This process significantly impairs the tree's photosynthetic capability.

Effective management strategies for controlling this pest include:

• Removing and destroying leaf litter in the autumn to reduce overwintering sites.
• Cultivating the soil around the base of the trees to disturb or destroy cocoons.
• Applying targeted insecticides when young larvae are present on the leaves.
• Promoting natural predators and parasitoids that help regulate the population density of the sawfly.