An inchworm has its way with a leaf in this picture provided by Alaska Cooperative Extension integrated pest management technician Micahel Rasy.
A close-up picture Rasy shot of a full-grown bruce spanworm moth.
Head-high alder can be the bane of hikers' existence. But due to a recent surge of geometrid moths in the Chugiak-Eagle River area, overgrown vegetation is not an issue. In fact, at higher elevations, it's nowhere to be found.
"Instead of it being in the full summer foliage, where it should be just overgrowing the trail, right now, it's nothing but bare branches," said Michael Rasy, statewide integrated pest management technician for the University of Alaska Fairbanks Cooperative Extension Service in Anchorage.
The moths have caused near-total defoliation of native species such as birch, willow and alder above 1,000 feet in some areas of Chugiak-Eagle River, Rasy said on a rainy Aug. 2 afternoon while surveying the damage near Hiland Road.
Below 1,000 feet, it's a different story.
"Below that, you hardly notice any damage," Rasy said. "Above that, it's complete defoliation."
Hiland Road is experiencing its second year of devastation. This year, areas near Arctic Valley Road and Eklutna have also been affected.
"It definitely has spread," Rasy said. "It's more widespread than we thought."
Rasy said the bruce spanworm, winer moth and autumnal moth are responsible for most of the damage. The moths, which start out in larval form as inchworm caterpillars or "loopers" sprang up in record numbers around Hiland Road in 2010.
"These loopers, they sort of go from zero to a thousand a lot of times in one year's time," Rasy said. "It's sort of their life strategy. They're at endemic levels and all of a sudden ... they just explode to epidemic proportions where they're just everywhere and they have complete defoliation in some local areas. That's exactly what we saw last year."
Rasy was first alerted to the problem last year after several Hiland Road residents called the service.
The ubiquitous inchworms resulted in "complete defoliation to the point that there was no foliage left on any of the plant material," Rasy said. "Even though it was summertime, it really looked like wintertime."
A closed forest canopy should surround Hiland Road houses. However, it's providing no cover for residents, Rasy said.
"They can see all the way to the other side of the valley, which they shouldn't be able to do," he said.
Similar outbreaks have been documented in Europe, Rasy said. He said geometrid moths have been seen in Alaska before but not on this magnitude.
"They've never behaved like this before," Rasy said.
Geometrid moths appeared in large numbers two years ago on the Kenai Peninsula, feeding mostly on salmonberries and blueberries, Rasy said. Moths have also been seen around Summit Lake and Turnagain Pass.
Massive defoliation of vegetation surrounds houses around the Hiland Road area of Eagle River. Typically in August, thick, green foliage usually covers the hillside.
Rasy said he believes outbreaks occur in three-year cycles.
"I think next year in some of those areas, especially on the Kenai Peninsula, we should actually see a significant decrease or should be almost impossible to pick up," he said.
But Chugiak-Eagle River is likely to have a repeat of this summer.
"I think definitely the Eagle River area should expect again to have heavy defoliation next year," Rasy said. "After that, we don't know what's going to happen."
The Cooperative Extension is currently documenting the situation and plans to study the ecological impacts the heavy defoliation may cause, Rasy said. Unfortunately, there's no basis of comparison in Alaska.
"We don't know in many instances," Rasy said of the ecological effect. "There are a lot of unanswered questions."
Though the situation sounds and looks bleak, some new growth is occurring, Rasy said. The native plants are resilient, he added.
"A lot of the plant material that was completely defoliated is actually putting on some new foliage," Rasy said.
Vegetation is growing what Rasy calls "survival foliage" to gain energy to make it through winter.
"The plant material is using stored energy to re-vegetate after losing all of its foliage earlier in the spring," he said. "It's doing that to gain energy to survive.
"It would take several years of this occurring to just completely use up the energy in that root system in a lot of these native species," Rasy added.
The current spell of cool, wet weather is the best scenario for the situation.
"Mother Nature right now is providing all that the plant material needs," Rasy said.
For now, homeowners have to wait. Action can be taken in spring 2012 by targeting caterpillars, which will be out in such large numbers one can hear them feeding on the foliage, Rasy said. Several products that target caterpillars are available, but it needs to be as specific as possible, he said. For more information about protecting against defoliation, homeowners should contact the Cooperative Extension at 786-6300 or visit www.uaf.edu/ces/anchorage.
Recent construction could also impact surrounding plants, making them more vulnerable to moth defoliation, Rasy said.
Some lag time exists for birds, insects and other natural enemies of moths to ease the situation. But ultimately, nature will run its course, Rasy said.
"Inevitably, the things that are going to bring the geometrid moth outbreak under control are these beneficial organisms," he said. "When you do anything to control the caterpillars, you want to minimize your impact that you're going to have on those."
Rasy is giving a presentation on the defoliation at the South Fork Community Council meeting Sept. 1 at 7:20 p.m. in room D107 at Eagle River High School, according to council president Andrew Brewer.
While the geometrid moth outbreak is a statewide issue, the scope of the damage is unknown, Rasy said. Aerial mapping will be conducted this summer in collaboration with the U.S. Forest Service for a better understanding of the scale of the defoliation, he said. Specifically, the damage in unpopulated areas and those with restricted access remains a mystery.
Crowberry is also suffering around Hiland Road. The low-growing evergreen is browning, but Rasy said it's unknown why. While it's not the preferred host for moths to feed on, Rasy said, the loss of other plant material from defoliation could be to blame.
For now, Rasy and the Cooperative Extension Service will continue to study what is happening to the vegetation and any potential ecological impacts from the recent moth outbreak.
Contact Mike Nesper at firstname.lastname@example.org
This article published in The Alaska Star on Wednesday, August 10, 2011.