Winter moth
Operophtera brumata
1 host plant
Last updated
Winter moth larvae emerge in early spring from egg masses, burrowing into expanding buds and feeding on new leaves for six weeks. You will see small, hole-ridden leaves and defoliation by late May in cool-climate areas. This European invasive causes significant damage to oaks, apples, and maples. Adults fly in late fall and early winter.
Monitor for egg hatching when daytime highs reach approximately 50 degrees Fahrenheit (10 degrees Celsius). Spray Bt when buds break and larvae emerge, then repeat every seven to ten days. Wrap tree trunks with sticky bands in October to intercept flightless females. Encourage native parasitoid wasps and Calosoma beetles.
Quick Reference
Four species of inchworms may injure blueberries, three of which are native to North America. The fourth, and potentially most serious, is the European winter moth, Operophthera brumata, which was introduced to the PNW in 1958. Adult males are small moths with light brown to tan colored wings which have a hairy appearance. Female moths have reduced wing size and are flightless. The larvae are pale green with a light stripe down their sides, up to 12 mm long. Larvae damage the buds, blooms,...
Cultural Controls
- General predators such as lacewings, assassin bugs, and spiders feed on the larvae, but populations are not well regulated by these predators.
- Cold winter temperatures may play a bigger role in controlling populations.
- Home gardeners: Pick larvae when you find them, and prune out infested growth.
- Management-