By Joseph Robertia
Photo courtesy of Janice Chumley, Cooperative Extension Service. A caterpillar munches its way through a leaf this fall. An outbreak of caterpillars earlier this year has resulted in a damaged blueberry and salmonberry crop this fall.
Redoubt Reporter
The invasion began in spring. After parachuting down on silken threads and then burrowing into soil, they emerged and began to wage their war in the thick canopy. Camouflaged in various shades of green they are almost undetectable in the foliage, but the wake of the damage they left behind is obvious and will take time to repair.
“It’ll probably be around two years to recover,” said Janice Chumley, integrated pest management technician at the University of Fairbanks Cooperative Extension Service in Soldotna.
She was referring to the damage done to native trees and shrubs by the caterpillars of Bruce spanworms and autumnal moths.
“Alder was their first choice, then willow, then they began dropping down and munching on other plant materials, including berry bushes,” she said.
The infestation appears to have begun on the lower Kenai Peninsula in 2009 and quickly spread, Chumley said, citing surveys conducted by CES, Native-owned Chugachmiut Forestry and the U.S. Forest Service.
The caterpillars have been documented in Anchor Point, Nanwalek, Port Graham, Ninilchik, Seward and mountain passes on the Kenai Peninsula, including Summit Lake and Turnagain Pass, she said. The insects have also been found farther north in the Anchorage, Matanuska and Susitna areas.
Chumley said the insects seem to have a preference for two berry bushes.
“It’s just been blueberries and salmonberries,” she said. “Lingonberries, high-bush and low-bush cranberries, currents and raspberries — they’re all doing fine. And, even with the blueberries and salmonberries, some areas have been hit hard and in others, it’s been spotty. And in the hard-hit areas, some have re-grown and others are still struggling.”
Chumley said that even in the areas where the vegetation has re-grown, berries may not come in well since the plants have been challenged by the insects nibbling away at their leaves earlier in the year.
“It’s a significant drain on the plant to have to put all that energy into producing leaves again. Instead of energy going toward berry production, it will go toward refoliation” she said. “So, depending on location, some berry crops are going to be impacted. People may have to hike a little farther than usual.”
While this may be a bit of a bummer to berry pickers, Chumley said it won’t be long until the situation resolves itself. Like snowshoe hares, which similarly run in cycles and cause defoliation damage to shrubs and bushes at their peak, the insects will soon eat themselves out.
“Like other geometrid moth outbreaks that have occurred in Alaska in the past, this current outbreak should run its course,” she said. “Areas on the southern Kenai should see a significant decrease in moth activity in the next year as they have had heavy defoliation for multiple years now. The northern Kenai Peninsula and Mat-Su valley areas will most likely have another year or so of heavy defoliation.”
Not all areas that have been ravaged by the bugs are void of berries. According to Chumley, a few people have reported doing very well in familiar areas.
“You just may not be able to go to the same place you’ve gone year after year,” she said. “But up in Turnagain Arm people have already done well, and in Seward some people have done really excellent at finding blueberries.”
