Maple borer

The Maple borer (Synanthedon acerni) is a wood-boring moth belonging to the clearwing moth family (Sesiidae). Adult moths exhibit batesian mimicry, evolving to look like wasps or hornets to deter predators, which makes them quite distinct during their brief adult flight period.

The primary hosts for this pest are maple species, including sugar maples, red maples, and silver maples. It frequently targets ornamental maples in landscapes, especially those suffering from stress due to drought, physical injuries, or improper pruning practices.

The biological cycle involves the female depositing eggs on the bark, often near existing scars or previous borer exit holes. Upon hatching, larvae bore directly into the inner bark and sapwood. They complete their larval development within the tree, often spending the winter as larvae before pupating in a silk-lined chamber near the bark surface during the spring.

The damage is primarily caused by larval feeding, which disrupts the tree's vascular system. Visible signs of infestation include protruding reddish-brown frass and sawdust around holes, as well as distinct lumpy or swollen calloused tissue on the trunk. Severe infestations can girdle the tree, leading to crown dieback or structural weakness.

Effective management strategies include:

• Promoting tree vigor through proper watering and mulching to prevent opportunistic attacks.
• Applying wound dressing or protective wraps to prevent egg-laying on damaged bark.
• Using pheromone-based traps to monitor population levels and timing for targeted insecticide applications.
• Removing and destroying heavily infested branches or small trees to reduce local population density.