WHERE’D IT GO?—Bill Dunker, biologist, peers into his collection jar to find an example of the green caterpillars that have been dining on willow bushes, making brown patches on the landscape in and about Nome.

Caterpillars taking Anvil Mountain, inch by inch?

The larvae of Geometer moths have stripped the leaves from patches of willows along Dexter Bypass and left the bushes brown.
Darrell Williams Sr. noticed the willows turning brown near his home on Dexter Bypass long ago, he said.
“I first noticed it along in March, when the season started to change,” Williams Sr. said Monday. Williams’ curiosity took him for a walk among the bushes to see what was happening.
“There were caterpillars. Lots of caterpillars,” he reported.
What color were the invaders?
“They were green. They were all green all over,” Williams Sr. said. Williams had been talking about the brown willows over coffee when he checked in at the Nome Visitors Center, and where folks talk about happenings about town.
The Nugget checked it out.
It turns out that if one knows the caterpillars well enough to use their nickname, they are called informally called loopers, span worms or inchworms because of the way they hump along in a loop step. One fascinated by the sight can watch them rise in the middle by pulling their hind end up towards their head, then scoot their heads along and do it all over again, as they inch along.
Formally, the caterpillars can be called their scientific family name, Geometridae, in Latin, comprising slender-bodied, broad-winged moths, the larvae of which are called measuring worms, because of the way they seem to measure the ground with their looping motion.
He doesn’t expect the caterpillars to permanently damage the willows, Bill Dunker, GMU 22 area biologist with Alaska Dept. of Fish and Game, said. It is an infestation that lasts some weeks and is over when the caterpillars become moths and take wing and take off. Dunker suspects it will be small gray moths that rise out of the caterpillars.
Meanwhile, the caterpillars are chomping up the green and leaving patches of branches and brown dried and damaged leaves on the hillsides, but not threatening the leafy nutrients moose browse on to any alarming extent.
“It seems to run its course and doesn’t tend to kill the willow,” Dunker said. “It will play itself out and the willows get their leaves back this season or next. It would affect the moose browse if it killed the willow. Some are already turning around this season.” True story, Darrell Williams Sr. said on his way down Front Street, going to work Monday morning
“Yes, they are starting to bud out green, right now, the buds are coming out green and coming back.”
Folks have observed the brown patches from the Nome River area westward to the Sinuk River. The inchworms pretty much stick to coastal areas, according to Dunker.
He is keeping tabs on the inchworms, he said.
When Tony Gorn, another state biologist returns from flying caribou surveys over the North Slope, Dunker intends to perform aerial surveys to determine the extent of the caterpillar infestation. For now, the patches appear here and there—by the old shooting range, along Anvil Creek, in and out of Osborn area and behind Williams’ house at Dexter Bypass Road.
“Time will tell. It’s just something we have to keep an eye on,” Dunker said.
The infestation tends to be limited to willows and just certain types of willows, he added.

 

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