Birch clearwing moth

The Birch clearwing moth (Synanthedon scoliaeformis) is a moth belonging to the family Sesiidae. These insects are well-known for their remarkable mimicry, as adult moths bear a striking resemblance to Hymenoptera, such as wasps or hornets, which helps them avoid predators while in flight.

The primary hosts for this pest are birch trees (Betula species), though it is occasionally observed on alder. The larvae are wood-borers, meaning they specifically target the inner bark and cambium layers of the host tree, causing internal damage that is not immediately visible from the outside.

The biological cycle of this species typically spans two years. After mating, the female lays eggs in crevices of the tree bark. Upon hatching, the larvae bore into the bark and begin feeding on the nutrient-rich tissues beneath, eventually constructing deep tunnels that serve as their living and hibernation chambers during the winter.

Damage caused by the birch clearwing moth is significant, as it disrupts the tree's vascular system. The presence of the pest is often signaled by frass (a mixture of wood shavings and excrement) pushed out from entry holes, and by the swelling or cracking of the bark. Severe infestations can lead to top-dieback, reduced vigor, and increased susceptibility to fungal pathogens.

Management of this pest involves cultural practices such as pruning and removing heavily infested wood during the winter months to reduce the local population. Pheromone traps are highly recommended for monitoring the flight period of adults, which is crucial for timing any necessary insecticide applications. Preventive measures focusing on tree health are the most effective long-term strategy.