MISSOULA, Mont. — European mantises are becoming a more common sight in Montana as warmer winters help the non-native insects survive and reproduce.
Glenn Marangelo with the Missoula Butterfly House & Insectarium said the species many people recognize is not native to Montana or the Americas.
He explained that gardeners used European mantises for decades to help control pests. Winter freezes used to kill their eggs, which meant people had to release them again each year.
“We wouldn’t get natural reproduction. Things have changed, look at last winter, how mild it is. For the last ten, 15 years we have been getting natural reproduction in Montana. They are essentially here to stay at this point,” Marangelo said.
Montana has two native mantis species. Marangelo said the minor ground mantis lives in the eastern part of the state and Skinner’s ground mantis lives in the west.
He added that those native species are much harder to spot.
Marangelo said it remains unclear what effect European mantises may be having on native mantises, but that other species might become meals once they get bigger.
“They’ll eat a lot of aphids [and] other things that you want to control. But the reality is, as they get larger, they’re going to eat bees that come to pollinate things,” Marangelo said.
For people looking for a native pest-control option, Marangelo pointed to convergent lady beetles often sold in garden centers.
“People are thrilled to see mantises, [they] are really charismatic. I love seeing them as well. It’s just we’ve got to realize this European mantis is a non-native species,” Marangelo said.
Marangelo said people will likely notice European mantises more in late August and September, when they go through their final molt and begin to fly.