BILLINGS — It seems there's been a bumper crop of boxelder bugs in the Billings area this season, but the recent October cold snap should kill a portion of the population that can't find shelter, according to James Barron, a biology professor at Montana State University Billings.
“I wouldn’t go so far as to say that the minute it gets below zero or below freezing, they’re all going to die. Some of them probably will be able to get through. But that’s not good for most of them. I mean, these are ectotherms. So their body temperature is pretty much what the temperature of their environment is. And if it gets down into the 20s Fahrenheit, that’s going to probably cause freezing in a lot of them and that will kill them," Barron said.
The bugs have been a particular nuisance for people across the area. Darby Schiesser, with Beartooth Pest Control was at the KTVQ building in downtown Billings last week to spray for boxelders and said this year, he's seen an increased number of calls for the bugs.
“We get called out specifically for boxelder bugs pretty regularly. Every day. As much as you want to work," Schiesser said.
“This year is just one of the top ones. We get them every now and then, but this is definitely more so than other years," Schiesser added.
Schiesser said many of the calls for boxelders have been coming from more rural areas. The sunny days and cool nights cause the boxelders to shelter on south or west facing trees or crevasses in homes to try and catch the last heat from the setting sun.
“I don’t know why there’s more this year, but we’ve had kind of a mild winter last year. I don’t know if more eggs survived or what, but this hot, long summer, everything's just kind of at its max right now," Schiesser said.
The boxelders are most active in autmn, when they are trying to seek shelter for the winter, according to the U.S. Department of Agriculture. They can move under rocks, steps, decking, sidewalks and into the interior of buildings.
Boxelders are mostly harmless to humans, feeding primarily off the seeds of the boxelder tree with no noticable damage to the tree, according to University of Minnesota Extention. But they can make their way into homes and they might wake up in the middle of winter if they are in a space with enough warmth.
Barron said he didn't have an exact reason for this season's bump in the crop of boxelders. His biology expertise is more focused on animals with a back bone, or vertebrates. Barron has worked for MSUB for 19 years and described his work as field ecology. He's studied horned lizards south of Bridger and an asexual minnow that lives in Montana.
“All I can tell you is that it was a good year for boxelder bugs. Every few years, there’s something that we seem to have a lot of. About 10 years ago, we had grass moths all over campus and all over town. These little small white moths and they covered buildings. Last year was really bad for grasshoppers. A couple years before that, it was yellow sweet clover," Barron said.
Barron listed a myriad of things that may have caused the boom. The long, dry summer could have done them some favors in that it was bad for the boxelder's predators and pathogens that normally keep the population down.
"Maybe last winter was a mild enough winter that a higher proportion of boxelder eggs and things survived to result in a much higher population this year. It certainly does seem, even out at my house, that there's an awful lot of boxelders," Barron said.
Barron said he also noticed a boom in another type of bug at his home: a leaf-footed bug.