Chief Meteorologist Lisa Teachman recently asked Facebook followers if they’d noticed an increase in moths this spring. Responses make it clear 2023 marks a banner year for an army cutworm miller/moth invasion. Great Plains residents can find scores of these creepy-crawlies tucked in every dark crevice in their homes, outbuildings, and vehicles. Observe drivers stopped at intersections. Windows roll down and waving hands shoo a handful of flying invaders outside where they belong. While humans see these as nothing but pests, grizzlies and black bears in the Rocky Mountain have a different perspective.
Every decade or so it seems, Great Plains grainfields and alfalfa patches host an exceptional hatch of army cutworms. Eventually these caterpillars morph into the seemingly dust-covered, wall speckling flibbertigibbets that drop from door lintels onto human necks and faces, an action that triggers the target to flap arms and slap wildly at the source of their gyrations. That sensation of multitudinous crawling legs and waving antenna brushing tender flesh is a nightmare come to life.
Anyone who’s experienced this or scrubbed greasy, brown moth plops off walls, windows, and lampshades has cursed these creatures. For what it’s worth, said bugs will get their due and not too far into the future. After spending 6 – 8 weeks tormenting residents of flyover country, these moths head to wild-flower covered Rocky Mountain slopes where they’ll sip nectar, enjoy cool temperatures, and tuck themselves into gazillions of fissures on a scree or boulder-filled incline. For a while, they’ll live the life of Reilly while victims left behind in Kansas roast under hot summer sun.
Sounds glorious until mid-August arrives. Shortening days, cooling temps, and perhaps some internal signal tells bears that also live in those mountains its time to pack on the pounds to prepare for winter torpor aka hibernation. Creatures that contentedly munched berries, grubs, grasses, and the occasional slow deer or elk suddenly crave high lipid calories. Those moths that drove plains folk nuts in May are 70% fat worth a ½ calorie apiece. One researcher called them “Lipid Chiclets.” Another “Bear Butter.”
Those dark hidey-holes on above-timberline slopes soon function as bear dining halls. Lumbering critters that entertained photographers and tourists at lower altitudes through June and July head for steep inclines to mine for moths. Scientists who study bear behavior and scat and record those efforts share that hyperphagic bears eat approximately 40,000 moths and pack on 20,000 fat calories daily for weeks.
Suddenly becoming a target must surprise insects who’ve spent the better part of summer enjoying chilly mornings, sampling wildflower nectar, and resting in the dark. Do moths about to be devoured hear bears clambering up their rock piles? What sounds do bear claws make as they lever through stony layers to reach that fat-scented insect? Does a moth have any sense of the devastating power of those teeth and that jaw before it slides down a bear gullet?
It’s been more than 20 years since I last researched and wrote about moths and bears. In the meantime, I’ve lived in grizzly country and watched them eat various meals. As I smack another moth to dusty smithereens, I can’t think of a better ending for its buddies who survive the migration to the high country.
Karen is a retired teacher, writer, photographer, outdoors lover, and sixth-generation Kansan. After a time away, she’s glad to be home.