Jim Hale noticed grasshopper nymphs in his field May 31, a day that reached — fittingly — 31 degrees Celsius. It was totally normal for him.
“I was unsurprised to see them,” said the farmer from the Lancer-Cabri area of southwest Saskatchewan. “I have had bad grasshoppers the past two years.”
WHY IT MATTERS: Parts of the Prairies have weathered recent cycles of building grasshopper populations.
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Hale isn’t alone. Grasshoppers have been a common crop pest complaint on the Prairies.
The Canola Council of Canada growers survey last fall asked respondents what canola insect pests they sprayed for in 2024. Flea beetles, unsurprisingly, were the most common answer. Of the farmers answering, 33 per cent pointed to the perennial canola bane.
Grasshoppers were a distant second — except in south and western Saskatchewan, where 39 per cent of respondents said they sprayed for grasshoppers in 2024.
Last year, Hale sprayed wheat and durum acres three times for grasshoppers — including once before the crop was even out of the ground. “It will be interesting to see whether my aggressive spray program last year will knock back the population for this year,” he said.
Back in 2023, grasshoppers came out of Hale’s tree rows and ate his wheat down to nothing.
“It looked like I had forgotten to seed around my trees,” he said, adding that the bare ground created “fabulous conditions for kochia.”
Early grasshopper start
This spring in Alberta, Dan Johnson, grasshopper expert and professor of environmental science at the University of Lethbridge, saw nymphs of the two-striped grasshopper species on May 7.
This was very early. An early hatch was also noted in Manitoba’s crop pest updates.
The good news is that a “good rain” in southern Alberta May 23 “cut off some of these early hatchers, and set them back to low levels,” Johnson said. “We went to 37 sites in Lethbridge County the last week of May, and another 20 across southern Alberta, and counts are all still low.”
Weather control for hoppers?
Wet conditions in early June can slow grasshopper growth and actually kill the smallest nymphs, Johnson said. Nymphs in the first two stages are prone to absorbing water or “sticking to wet substrate surfaces, which encourages fungal infection.”
Looking ahead, wet conditions in July slow maturity of larger grasshoppers, which delays egg laying. Wet conditions in August interfere with mating and egg production. August wet conditions combined with warm weather can increase infection by the grasshopper fungus Entomophaga grylli.
“This fungus is usually rare but can erupt in isolated cases,” Johnson said.
Grasshopper pressure from the past
While wet cycles last summer did set back the grasshopper population, dry conditions in late summer “were excellent for egg-laying,” said Jim Tansey, provincial insect specialist with the Saskatchewan Ministry of Agriculture.
Grasshoppers have one population cycle per year, with egg laying in late summer or fall and hatch the following spring.
Each female can lay 100 to 150 eggs and sometimes as high as 400, Johnson noted, and egg survival could be very high this year.
“We could see a rapid population rebound, especially if conditions are warm and dry,” Tansey also said.
Amanda Jorgensen, the new insect management specialist with Alberta Agriculture and Irrigation, reported in the last week of May that, “I have seen second instar two-striped grasshopper nymphs in Westlock county (north of Edmonton). The heat and overall low precipitation is allowing for very advanced grasshopper development.”
Jorgensen said dry areas are at a high risk. Plants are less able to tolerate feeding.
She urged producers to scout.
Scouting for grasshoppers
Tansey has a simple approach to scouting: If grasshoppers are present at numbers and crop damage is accumulating, spray.
“Accumulation of damage is the most important consideration, because not all species are pests in all crops,” he said.
They may be present in crop, but won’t be eating. Two-striped and clear-winged grasshoppers are the two primary pest species on the Prairies.
If you want to get serious and actually count the pest hoppers, the Prairie Pest Monitoring Network recommends this protocol:
• Mark off a distance of 50 metres with flags on the road or field margin.
• Walk along that 50-metre distance, counting grasshoppers within a one metre square in front of you. A preferred option is to take separate counts for each one-by-10-metre segment, providing five counts per 50-metre stretch. Make some disturbance with your feet to encourage any grasshoppers to jump. The grasshoppers per square metre will be the average of all your counts.
• Do the above in the ditch and again inside the crop. Repeat further down the road and possibly again in the middle of the field. This will determine if grasshoppers are confined to field margins.
• To confirm grasshopper growth stages and species, use a sweep net to capture a few to examine more closely. Contact a provincial or local extension expert if you want help with identification.
Most grasshopper species are not crop pests, so confirm crop feeding before making a spray decision, the farmer resource suggests. Grasshopper nymphs also look like leafhoppers, it warns.
Economic spray thresholds
The current threshold for grasshoppers in canola is eight to 12 adults per square metre. This is based on counts in mature crop.
This threshold does not apply to nymphs eating small plants early in the season, but these nymphs can still cause economic loss.
The threshold concept does not apply very well with grasshoppers, Johnson said.
“I have seen five per square metre cause losses and I have seen 100 per square metre cause no loss. It depends on species, weather, and stages of crop and grasshopper,” he said. “Damage is the key thing to look for, and it is often mainly around the margins.”
In 2024, the Prairie Pest Monitoring Network floated a new approach to thresholds:
• Twelve to 14 fifth instar nymphs and adults per square metre of crop is suitable for average or above-average growing conditions.
• Thirty to 45 nymphs per square metre has been proposed to remove the threat early when grasshoppers are small and easy to target. This also allows for a larger suite of insecticides. For example, Group 3A (synthetic pyrethroids) insecticides are not recommended for adult grasshoppers, but they could help earlier in the season.
• Ditch thresholds of 24 to 50 fifth instars and adults, and 50 to 75 nymphs per square metre, are also in discussion. With a ditch threshold, farmers could consider an early targeted spray before pest grasshoppers move into fields.
If all that counting seems too much, go back to Tansey’s approach. Do you have lots of grasshoppers? Are they actually damaging your crop?
Grasshoppers often lay eggs in ditches or tree lines, so nymphs often concentrate in or near ditches early in the season. Targeted sprays are sometimes effective. For Hale’s early season sprays for grasshoppers, he takes what he calls a “ditch-to-ditch” (rather than “corner-to-corner”) approach in fields that require a spray.
For more, farmers can look for “Grasshopper management in canola” in the insects section of canolawatch.org/fundamentals.
Jay Whetter is a farm journalist based in Winnipeg and communications manager for the Canola Council of Canada.
