Locust clearwing moth

Systematic position: The locust clearwing moth (Paranthrene robiniae) belongs to the order Lepidoptera and the family Sesiidae. These insects are biologically fascinating due to their mimicry, appearing strikingly similar to Hymenoptera, such as wasps or hornets, which aids them in avoiding predators while active during the day.

Host plants: The primary host is the black locust (Robinia pseudoacacia). However, the pest has been reported on various other deciduous tree species, including poplars and willows. It is considered a significant pest in both ornamental urban forestry and commercial tree plantations where its presence can jeopardize tree health.

Biology and life cycle: The insect spends most of its life cycle hidden within the host tree. Adult moths emerge in late spring or summer to mate and lay eggs on the bark. Upon hatching, the larvae bore into the sapwood and heartwood, creating extensive galleries. They overwinter as larvae inside the wood before pupating in the spring.

Damage and severity: The primary damage is caused by larvae feeding on the inner bark and sapwood. This boring activity disrupts the vascular system of the tree, potentially leading to branch dieback or total decline. Furthermore, the boreholes serve as entry points for secondary pathogens, such as fungi, which accelerate the rotting process within the stem.

Management strategies: Controlling wood-boring clearwing moths requires careful monitoring and timing:

• pruning and disposing of infested branches during the dormant season;
• maintaining tree vigor through proper irrigation and fertilization;
• applying systemic insecticides during the peak adult flight period;
• utilizing pheromone traps to monitor population density and determine the optimal timing for interventions.