Fall cankerworm

Systematic position: The fall cankerworm (Alsophila pometaria) belongs to the order Lepidoptera and the family Geometridae. It is a well-known forest and orchard pest that can cause significant damage to deciduous trees throughout its range, primarily in North America.

Host plants: This insect is a generalist feeder with a broad host range. It frequently attacks a variety of hardwood species, including apple, cherry, elm, maple, oak, and ash. Its ability to thrive on diverse hosts allows it to maintain large populations in both urban landscapes and natural forests.

Biology and life cycle: The species possesses a unique biological trait: adults emerge and mate during late autumn. Females are wingless and crawl up the trunks of host trees to deposit eggs in masses on the branches. These eggs overwinter and hatch in the spring, synchronized with the bud burst of the host trees, allowing the larvae to feed on newly developing foliage.

Damage and economic impact: The damage is primarily caused by the larvae, commonly known as inchworms. They feed on buds and leaves, often skeletonizing them. During outbreak years, high populations can cause complete defoliation of trees. Repeated defoliation weakens trees, making them susceptible to secondary diseases and pests, reducing fruit yield, and potentially leading to tree mortality.

Control measures: Effective management of the fall cankerworm requires a combination of strategies. Key approaches include:

• Applying sticky adhesive bands to tree trunks in the fall to trap wingless females as they attempt to climb to the canopy.
• Monitoring larval activity in the spring and applying targeted insecticides if populations exceed economic thresholds.
• Using biological control agents such as B.t. (Bacillus thuringiensis) to minimize impact on beneficial insects.