GRAND FORKS – Now that an autumn influx of small, brown moths is over, a UND biology professor says it might be a more common sight in the future as the region’s weather grows warmer by the year.

Rebecca Simmons, who specializes in insect evolution, mimicry and courtship behaviors, said she and some of her fellow professors noticed the increased number.

“I think we’re going to see a lot more different kinds of insects here that we’ve never seen before,” she said. “I’m seeing a lot more yellow swallowtail (butterflies). I’m seeing a lot more praying mantids. We’re not supposed to see praying mantids up here – it’s too cold. But now people are showing me them because it’s finally warmer and the winters are getting milder and milder.”

The moths converged on Greater Grand Forks and the region last month, in some places congregating on the ground and in others crowding at low altitude. Simmons said this autumn’s mild temperatures were just right for the moths to develop and exit their chrysalises. Insects have “degree days,” days of the proper temperature for them to grow and be active, she said. A string of days at the right temperature leads to more activity, eating and breeding. The good weather and proper food sources combined to keep the moths in action longer.

Simmons said this year she saw more generations of moths than usual.

What kind of moths were they? Simmons said she set out to figure out which moth species it was, but the task wasn’t easy.

Simmons recently told the Herald the moth belongs to the family Erebidae, one of the biggest families of moths. The moths’ most noticeable features are their small size and brown coloration, making them hard to tell apart from other species.

“That whole lineage probably has 100 to 200,000 species in it worldwide,” she said. “How do you tell them apart? It can be really tricky. … You have to focus in on whether they have a wavy line, whether their hind wing is dark, or little details like that.”

Her best guess as to the specific moth is the green cloverworm. It’s grouped along with other “snout moths,” named for their noticeably long snouts. It took some effort to identify it among the multitude of possibilities.

Simmons began by walking around Starcher Hall, home of UND’s Biology Department, collecting the moths off the floor to examine. She compared the moths she found to specimens in the department’s collection.

She also used a microscope to get a closer look at the moths’ features, such as their scales. Moths and butterflies have small scales that give them their colors, Simmons said, which can come off when someone touches the specimen. She had to be careful not to rub off the scales while she worked.

Through examinations, comparisons and reading through her books, Simmons came to the conclusion that the green cloverworm was the moth that seemed to be in abundance. The reason for the higher numbers was a mix of food availability and weather. Green cloverworms eat foods like alfalfa and clover, both of which were available nearby.

September’s mild temperatures fit into the green cloverworm’s degree days, meaning they could develop and exit their chrysalises, with time to be active and create more generations than usual.

As for the other insects Simmons and others have seen, she believes the addition of new and different crops being grown in the region also attracts different species along with the warmer weather. These insects usually don’t migrate as far as North Dakota, but the combined factors have them traveling past their usual limits. She expects the region will continue to see increased numbers of new insects in the future.

Otto is a recent University of North Dakota graduate and reporter at the Herald.