I've received a couple of alerts recently from Jim Esden, Forestry Specialist with Forests, Parks and Recreation, about hemlock wooly adelgid. (Jim has given a number of workshops on the pest in Bennington County.)
Now is the time, he reminds us, to be looking for the insects. The tiny organisms are hard to see without magnification, but their protective covering – a bit of white fluff about the size of a pin head – is easily observable now and for the next several weeks. (Look for the fluff at the base of the needles, on their undersides.)
I had his messages in mind a few days ago when I went for a snowshoe on the Broad Brook trail in Pownal. There, the snow depth was such as to put me at nose height with hemlock branches I'd not been able to reach before, on other outings.
I'll go back to survey some of those trees another day soon, when I've got my gear and a good-sized chunk of time. Though Jim's department is glad to get any information on the pest (which has been found only in the southeastern parts of Vermont), it prefers that surveyors follow a protocol: examine 200 branches, each at least a meter long, on no fewer than ten trees. It takes a while.
I really love hemlock the tree. And I know what an important ecological niche the species occupies – "rushing headwaters stream" and "dark, cool hemlock glade" are, for example, nearly indivisible. As a result, I'm inclined to deny that hemlock wooly adelgid might one day take hold here.
Which is why I was glad indeed to wake up to -24 degrees F that Monday morning in late January. And cheered to hear about similarly low readings in Readsboro and Woodford and elsewhere around the state. I imagined the little buggers expiring inside their fluffy muffs like the witch dissolving in the Wizard of Oz.
Jim reluctantly set me straight. "I don't think the cold we've been experiencing," he told me, "is going to make a significant impact on adelgid populations."
Lab studies suggest that lots of things have to go right with the thermometer for the adelgid to take a nose dive. Very cold, for a long time, and late in the winter are the necessary, but not always sufficient, ingredients. (Some pests survived even these conditions in experiments.) Even where winter minimums average -26 degrees F, the insect has expanded its range, though somewhat more slowly than in warmer climes.
And as we know, warmer climes are the trend.
Still, there are no hemlock wooly adelgid in Bennington County yet (she said defiantly, maybe fearfully). But let's confirm that, shall we?
By becoming a hemlock wooly adelgid surveyor, you'll get to spend time in the woods in the winter. You'll work on a task that will focus your mind and your senses. And you'll contribute to the common good while wearing snow shoes. (Or not. Birds seem to carry the pest from place to place, so even trees near the backyard birdfeeder are worth examining.)
My office can provide you with the tools you'll need, including tree identification sheets, survey forms, hand lenses, reporting envelopes, and sample bags. (Old spider egg sacs, for example, look something like adelgid fluff. Forests, Parks and Recreation staff will examine your ambiguous finds and report back to you.). We can accompany you in the field on your first outing. Or, for those wanting a little more support, we'd be glad to ask Jim Esden down to give a workshop on the adelgid. (We can ask him to accentuate the positive.)
Shelly Stiles is the district manager for the Bennington County Conservation District, whose mission is promoting rural livelihoods and protecting natural resources in southwestern Vermont. For more information on surveying for hemlock wooly adelgid, contact the district at 802 442-2275 or firstname.lastname@example.org.