Cherry Bark Tortrix – (Enarmonia formosana)
The Cherry Bark Tortrix (Enarmonia formosana) is an invasive species native to Eurasia, first discovered in British Columbia in 1989. Since then, it has established itself as a significant pest in the Pacific Northwest, particularly in urban area where ornamental cherry and other rose-family trees are common.
This insect targets the living tissue beneath tree bark. Eggs are laid in bark crevices and hatch into larvae that feed on the phloem and cambium, never penetrating into the hardwood. Larvae overwinter beneath the bark and mature in early spring, eventually pupating inside reddish-orange frass tubes. Adult moths emerge soon after, with summer flights marking the peak of their life cycle.
The eggs begin milky white and pink or red within a few days. Fully grown larvae are just under half an inch long, pale grey to pink with dark heads. Adults are small, mottled brown moths with coppery wing spots and a wingspan just over half an inch. Their wings are marked with metallic grey patterns and three parallel black bars near the tips.
Infestation signs often appear around previously damaged bark. These signs include frass tubes, curling or cracked bark, cankers, and oozing gum-like resin. Damage can lead to branch dieback, trunk girdling, and in severe cases, tree death. While the pest rarely kills healthy trees outright, it can leave them vulnerable to secondary infections and environmental stress.
Preferred host species include cherry, apple, crabapple, hawthorn, mountain ash, pear and photinia. In urban landscapes, ornamental cherry trees are particularly at risk.
Management involves early detection and consistent monitoring. Pheromone traps in spring and fall can help trap adult activity. Infested bark should be removed, and damaged areas can be treated with pruning seal. Dormant oil sprays may also help reduce larval populations. In heavily infested cases, removal of the host tree may be the most effective option.
Although still under the radar for many property owners, the Cherry Bark Tortrix is a serious pest with the potential to impact both ornamental landscapes and fruit production.
If you suspect your trees may be affected or are seeing unusual bark damage, it’s best to reach out to an arborist that can help assess the situation and recommend effective treatments.
