Abundance of "miller moths" around Lake Tahoe this year

SOUTH LAKE TAHOE, Calif. - If they were flowers on the ground or money in trees, most would welcome them. But they aren't. And love them or hate them, they’re back!

Miller moths, or the army cutworm, have become a nuisance in many parts of Lake Tahoe over the last few weeks, but not all areas have been affected. Those who have them around their homes are seeing dozens each night, swarming around their lights both inside and outside.

In May, Colorado saw an earlier migration of the miller moths and numbers far exceeding previous years, some homes reporting one hundred moths every evening. In June, they started showing up in Lake Tahoe, mostly at elevations above lake level neighborhoods. Houses in Al Tahoe may not be seeing them, but houses up Keller or in Meyers see dozens inside their homes each night.

"They are always going for greener pasture," explained Shaun Winterton, insect biosystematist with the California Department of Food and Agriculture. He said the army cutworms love corn, plentiful grasses, lusher vegetation, and moisture, something not all areas have and a reason they start migrating uphill as things start to dry out in the Sacramento Valley and Carson Valley.

They are very attracted to flowing plants. Who knows if everyone staying at home this spring and gardening during the pandemic created more food for them?

Winterton said it is hard to predict insect migration, especially during climate change. While the army cutworm is a strong flyer he said the heavy infestation in Colorado, which originated in Kansas, is not related to the increasing numbers in Lake Tahoe.

"Many insects are very good at capitalizing on favorable conditions (e.g. the California Tortoiseshells last year), and this year appears to be a good one for army cutworm moths," said Dr. Will Richardson, executive director of the Tahoe Institute for Natural Science. "Army cutworm moths are definitely one of those species, and big outbreaks are definitely regular every handful of years. Over winter survival and caterpillars having enough food to reach adulthood is the key to a big outbreak year."

"At Tahoe, we notice these sorts of outbreaks even more so in highly migratory species that travel upslope," said Richardson. "Again, the California Tortoiseshell is a great example, but army cutworms do something similar, and the moths that are so conspicuously descending upon South Lake and Incline right now may have traveled from way out in the Carson Sink, or possibly even further in the Great Basin.

The moth gets its nickname "miller moth" because of the fine scales on its wings that rub off easily and remind people of the dusty flour that covers the clothing of a miller.

"They should settle down in another 2-3 weeks, but in the meantime, we can be grateful for the supplemental bird, bat, and bear (etc.) food that is flying into our area," said Richardson. "And yes, bears definitely eat these moths. In the Rockies, Grizzlies will travel up to high talus slopes specifically to hunt for aggregations of them. Closer to home, everything from Flammulated Owls, to Cat-faced Spiders, to our two species of skunks likely benefit from this influx of easy fat and protein."

"Flight activity of this moth will accelerate with periods of warm nighttime temperatures. When there are cool, wet periods – particularly where there are abundant sources of plant nectar - the migration will tend to stay in place for a while. Ultimately, all will end up in higher elevation areas where the army cutworm moths feed and rest throughout summer, returning to the lower elevations in early September when they will lay eggs," said Colorado State University Extension Entomologists Whitney Cranshaw and Frank Peairs in May.

The following is from long-time local resident Jim Barr about the moths and how they've made evenings not very enjoyable:

I’m normally a pretty easygoing guy. I’ve been known to release spiders from my bathtub. (How’d they get in there, anyway?). I’ve stopped a tennis match to escort a caterpillar off the court. And if there’s a fly on my screen door, I’ll open it and send the flying pest off to say hello to a hungry Chickadee.

But I draw the line when it comes to “Moths.” They’re on the wrong side of that line. Unfortunately, and for whatever reason, we’ve had an infestation of them. But it’s not like they’ve taken over the entire home. For them, “Club Med” is a corner of our living area where, of course, we relax nightly.

Reading up on these annoying insects, I learned that there are 160,000 species and they fit into discrete categories. For example, there are “Large and Dramatic” moths. My first thought is that you don’t need two adjectives to describe them. “Large” alone is enough to make me leap out of my chair as it lands on my shoulder. I have no idea if the “Dramatic” moths put on a little performance before flying into my ear, but I’m not interested in buying a ticket to find out.

Reading further, I noted that there are also Fictional Moths, like Mothra, the recurring character in the Godzilla franchise. Thank you very much, but there’s nothing fictional about these brown bombers I deal with nightly.

As evening arrives on soft, slippered feet, we cautiously turn on a light in the living area. Doing so alerts an entire squadron of moths standing by in their Ready Room. They’ve been waiting all day to begin their aerobatics. Despite my deep dive searches during the daytime, I cannot find a single one of these pests in slumber mode.

Suddenly, the Netflix show we’re watching has attracted several new performers, and they’re crawling over the detective’s face. Meanwhile, a stray wanderer has peeled off from formation and is flitting around the wounded guy on the floor. No scriptwriter has added these characters and they add nothing to the storyline. Soon, I find myself watching the moth display and have forgotten the entire movie plot.

I leap into action with my tennis racquet-shaped, battery powered “Zapper.” With each contact, there’s a Zap! sound and one of the enemy hits the deck The smell of toasted moth hangs heavy in the air and will never be an air freshener fragrance. Discovering there’s safety in numbers, the reserves are called out and I’m now swinging my Zapper with an advanced Eastern Forehand grip and no time to switch grips for a backhand. As the herd thins, the remaining moths, probably in contact with each other, all flit to nether areas where they remain unseen.

That’s my cue to rewind the movie and see what the detective looks like without a moth trying to crawl up his nostril.