Grasshoppers swarm Lethbridge

Long stretch of hot weather improves growth, survival rate of hungry insects

Areas of Lethbridge are crawling with grasshoppers after weeks of hot temperatures sped up population growth, leaving residents struggling to get a grasp on what to do.

Lethbridge resident Trevor Lewis lives in Garry Station, where he said the infestation is particularly dense. Two weeks ago, he said the leaves on the roses in his garden were stripped by the grasshoppers. Since then, it's been “a daily battle,” he said.

“Ate all the roses, half the beans before I started killing them,” he wrote in a message to Postmedia. “It was the worst I've seen.”

Now Lewis tries to control them by trapping them in bottles, but it's become difficult for his family to even go outside, he said.

“My wife won't leave the house. My kids won't play in the backyard.”

Meagan Williams, spokeswoman for the City of Lethbridge, said the issue stems from an extended period of extremely hot, dry temperatures combined with poor crop yields.

“Because of this, farmers who would usually spray pesticides/ insecticides haven't done so,” according to her statement.

Residents are encouraged to reach out to pest management firms or garden centres for control options, according to the city.

“We acknowledge that residents want to be able to enjoy their outdoor space in the summer and encourage them to utilize other outdoor spaces in our community,” she said.

Dan Johnson, a professor of environmental science at the University of Lethbridge, has been studying grasshoppers for decades. He organized and chaired the world conference on grasshoppers and locusts held in Canmore in 2005, and made the first geographic information system (GIS) to forecast insect populations in 1986.

Johnson said the species of grasshopper causing the damage is the two-striped grasshopper. This kind of grasshopper rarely flies far, but can walk well into a crop as it feeds along a band. Considering the effects the drought has had on neighbouring farmland, the grasshoppers have moved into green front lawns and gardens, looking for fuel.

“It's almost like fighting fires, right? Most of the time, they can be controlled,” he said. “But if they do completely get away over a large area, there's not much you can do.”

Populations have exploded before, in the 1980s and the 1990s. Infestations tend to happen every five years or so, and signs of population buildup were there in March, Johnson said. But this outbreak is different.

“They've never really had a long, hot run like this, and it boosted them up. It wouldn't have, except for the fact that they had a couple of years to slowly build,” he explained.

Grasshoppers are cold-blooded and normally have to sunbathe to warm their body temperature. With the heat wave, they were perfectly happy to eat more food, and therefore, develop faster. The heat also increases their survival and works against their natural enemies.

“Next, they'll be laying eggs more rapidly,” he said, which could set the groundwork for larger infestations in the future. One female grasshopper can lay anywhere between 35 to 50 eggs.

While out doing a survey in Lethbridge, Johnson said he's counted as many as 100 grasshoppers per square metre in some areas.

“That is so far past the level of being of concern. If we see 20 per square metre, it's considered to be a significant problem.”

But these grasshoppers are not blanketing the city; they're hyper focused in some hot spots spanning a few miles, Johnson explained. According to a 2021 provincial grasshopper forecast, populations seem to be focused south of Calgary, and more heavily in the southern parts of Lethbridge.

The swarms of grasshoppers won't dissipate until temperatures drop, though water and rainfall seem to “slow them down,” he said.