Manitoba's grasshopper count keeps creeping up, provincial entomologist says

A Manitoba Agriculture entomologist predicts another year of high populations of grasshoppers.

Western part of province expected to be most severely affected

The province has been tracking and forecasting grasshopper populations in some form or another since the early 1930s, says entomologist John Gavloski. Here, a grasshopper from the subfamily Gomphocerinae, or slant-faced grasshoppers, perches on a twig. (ASakoulis/Shutterstock)

Grasshoppers will likely continue to spring up en masse this year due to a series of hot, dry summers, a Manitoba Agriculture entomologist says.

For the last two years, the provincial grasshopper population has been rising, John Gavloski told CBC.

"For two years now populations have been climbing. And if we get favourable conditions that trend potentially could continue," he said.

Gavloski predicts the western part of the province will be most severely affected by high counts, particularly the southwest portion around Brandon, Virden and Russell, as well as the Interlake region.

Grasshopper surveys have been conducted in Manitoba in various degrees of detail since 1931, says the website for the provincial government's Agriculture Department.

The forecast is based on a number of factors, including:

  • Counts of grasshopper populations in August, which help estimate the egg-laying population.
  • Weather data, which helps estimate whether those female grasshoppers present are capable of laying their optimum level of eggs.
  • Recent trends in grasshopper populations.

Counts are generally done in or alongside crop fields in Manitoba.

This map forecasts Manitoba's grasshopper hot spots for this year. (Submitted by Manitoba Agriculture)

It was roughly a decade ago the last time the province became concerned about a potentially worrisome projection, but that situation was narrowly averted thanks to heavy precipitation.

"Some very heavy rains in June decimated the population," Gavloski said, adding that can happen if lots of precipitation falls after the insects' eggs have hatched.

High grasshopper populations can affect a lot of different kinds of crops, including cereal, pulse and oilseed crops.

"They can affect a lot of crops and potentially be quite significant," he said, and canola is one of their favourites.

"Soybeans aren't necessarily their favourites, but they will feed on them if their other food sources aren't abundant or mature or harvested."

Gavloski advises producers to scout field edges and ditches early and prepare to apply insecticide.

The forecast is issued each winter to estimate levels of the four species of grasshoppers that have potential to be pests of crops in Manitoba, said a recent December report.


  • We initially reported that high grasshopper populations can affect pulp crops when in fact, they affect pulse crops. Additionally, we reported canola is a cereal crop, when in fact it's an oilseed crop.
    Jan 13, 2020 1:31 PM CT

With files from Gavin Boutroy


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