An insect infestation which was first reported in 2020, will continue to cause damage to a variety of trees throughout the Tongass this summer.
Last summer’s unusually warm weather fueled an explosion in the Western blackheaded budworm, leaving masses of browning trees in many areas of Southeast. The worm, which is the larval stage of the budworm moth, is known to feed on the new growth of trees, leaving them with a brownish-red appearance. While they’ve been known to target Hemlock trees Dr. Elizabeth Graham, an entomologist for the USDA Forest Service Alaska Region, says budworm seem to be moving on to spruce this year.
“This is possibly the result of, you know, depleting the resource. There was so much defoliation on Hemlock last year. And so the females may have chosen to lay their eggs on spruce instead, since there’s maybe more of a foliage resource available than with the Hemlock,” explained Graham
According to the Forest Service, this is the first large scale outbreak Southeast has seen since the mid 90s. While the damage may seem severe as worms continue to feed over the coming weeks, according to Dr. Graham, these infestations are a natural part of the changing forest.
“They’re basically a cool driver of change, that they’re creating new gaps in the canopy, adding some more light to the forest floor, adding some more fertilizers to the forest floor. And so there, there are many ways can be beneficial,” she said
The infestations occur on a 30-to-40 year rotation. Graham says they usually persists over the course of several years before naturally crashing, but she’s hopeful that we’re in the peak stages
“We’re kind of seeing that since they’re switching over to spruce now, and so they just can’t sustain at these levels. And so hopefully we’re reaching the peak,and that, you know, maybe this will be the last year,” said Graham. “But we’ll see how it goes and, you know, keep monitoring, and eventually it will definitely drop off. They just can’t last that long.”
While most trees are expected to survive the outbreak, the Forest Service is encouraging visitors to document and share their observations of insects and tree damage through the iNaturalist app. Photos, videos or information related to the budworm or its subsequent damage that is uploaded to the app will automatically be included in the Alaska Forest Health Observations Project, a citizen science project in iNaturalist.
