Bud-worms defoliate Southeasts hemlock

    A western blackheaded budworm shelters in western hemlock needles tied with silk. (USDA Forest Service)

    Juneau, Alaska (KINY) - Hemlock populations around southeast Alaska have been impacted by an insect called the western black-headed budworm.

    "The name budworm refers to the fact that they start off eating in the bud of trees, specifically they prefer hemlock but we can also get them in our Sitka spruce here, and the caterpillars will hatch, right around the same time that the buds burst and then they'll move up and mine the buds and then they'll start feeding on the new foliage as the needles elongate," said USDA forest service, forest health protection team etymologist, Dr. Elizabeth Graham.

    The budworms aren't the first insect to impact the hemlock,

    There have actually been multiple things that have been impacting our Hemlock in 2018 and 2019, we had an outbreak of hemlock Sawflies, and that's also defoliator or that's endemic to our forests here, and usually, it's at low levels and doesn't cause many problems, but their population built up and they feed on the older needles," said Graham. "And the reason why that's important is that we have hemlocks that are already thinned and stressed from that sawfly outbreak, they spent on those older needles, and now  the Western Black-headed budworm outbreak, they're feeding on the newer needles and so the two of those together can cause some heavy stress on these trees."

    Graham noted that both of these insects are native to the Tongass, and play an important role in the ecosystem

    "But that being said, these are both pests that are part of our forests. As I said, they're both endemic and we've been having these outbreaks you know we've been recording them for the last 100 or so years and they've been occurring even longer than that, and so we know that these happen, and they're a part of the dynamic nature of our forest and so we don't have a lot of other agents that drive change and so these defoliator outbreaks, end up creating pockets with new light that can get in, allowing new trees to grow in and understory plants to develop and most of the trees will actually recover from this outbreak and sort of fill back in eventually," said Graham. "But it's pretty impressive when you see something of this magnitude and then also, right now what we're seeing is the all the adult Western black-headed budworm moths flying around, and this is really probably just the first year of that outbreak that we're expecting we'll be seeing more of this next year."

    Graham will be talking about the budworms, tonight during an Evening at Egan lecture, starting at 7 pm.

    More information can be found at www.uas.alaska.edu/eganlecture.

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