The tiny, grey weevil was the greatest pest problem of the 2025 growing season, said Manitoba Agriculture entomologist John Gavloski.

“My poor summer students this year [found] 1,739 weevils in our 27 fields,” Gavloski told an audience at the 2026 Manitoba Ag Days in Brandon in January. “They were over double the economic threshold.”

WHY IT MATTERS: After a few years of minimal presence in Manitoba, cabbage seed pod weevil populations boomed in Manitoba in 2025 — in one case to twice the economic threshold.

Cabbage seed pod weevil is a three- to four-millimetre insect that lays its eggs inside young canola pods where its larvae feed on seeds. It overwinters as an adult under leaf debris and moves into flowering canola fields in late June and early July.

Gavloski’s survey results showed a dramatic population boom in 2025. In one field north of Carman, the count was as high as 226 weevils in a 25-sweep sample.

The economic threshold for cabbage seed pod weevil damage is 25 to 40 weevils per 10 sweeps, or 63 to 100 in the 25-sweep samples Gavloski’s survey uses. That Carman-area field was more than double the economic threshold and was treated once the population was confirmed.

Prior to 2025, the highest single-sample count Gavloski had recorded in his surveys was six weevils.

The pest has also been spreading eastward across the province. While populations were historically confined to southwestern Manitoba, weevils were detected as far east as the Ste. Anne area in 2025.

Scouting the critical first step

The weevil arrived in Manitoba from Alberta, where it had spread after an introduction to southern British Columbia in the 1930s. By 2017, it was first detected in Manitoba near Morden.

Survey counts remained very low for years before last season’s surge.

“We went from low counts to really high counts in the Carman area, going from 2024 to 2025,” Gavloski said.

“So bottom line, watch your fields. Start learning how to scout your fields.”

Scouting is complicated by the weevil’s defence mechanism: when disturbed, it drops to the ground and plays dead. Finding a three-to-four-millimetre grey insect on bare soil is no easy task.

“Just walking the field without a net, you could have a lot of them there and really not know it,” Gavloski said.

He recommends producers use a sweep net and conduct 10 sets of 10 sweeps: five near the field edge, five farther inside, during the flowering period in late June and early July.

Research from Alberta suggests that trap cropping (seeding the outside rows of a field one to two weeks earlier than the main crop, then spraying only those edges) can concentrate weevil populations and provide effective control while protecting pollinators in the main field.

Seeding date is another factor. Earlier-seeded canola, which flowers first, attracts significantly more weevils than later-seeded crops.

While cabbage seed pod weevil dominated the conversation, Gavloski noted several other insects that warranted attention across Manitoba during the 2025 season.

Flea beetle damage lessens, cutworms trend down

Flea beetles remained a concern but caused less economic damage than in recent years — largely due to a warm, moist spring.

“I don’t think it was because the flea beetle populations crashed,” Gavloski said. “I think it was because we finally got a season where people seeded the canola, it came up, and it seemed to have enough moisture and enough heat to get you from seedling to three to four leaf stage relatively quickly.”

Cutworms were still present and some fields were treated, but Gavloski said populations appear to be on the downward side of a cycle. He compared cutworm population dynamics to a bell curve: populations build, peak for a few years, then taper off, often driven by natural parasitoid activity. The worst years were 2020 and 2021.

“We’re kind of on that downward curve,” he said. “Populations have dropped off a little bit.”

Western and southwestern Manitoba bertha armyworm hotspots

Bertha armyworm became a regional concern, particularly in the western and southwestern parts of the province around Gladstone, Neepawa, Holland and Brandon. Some activity extended toward the central region.

Traps Gavloski monitors showed many locations crossing into the “uncertain risk” category during the summer. He noted some positive signs, however. There were reports of armyworms found dead on top of plants — a sign that naturally occurring viral and fungal pathogens had gotten into the population.

“If they’re up on the top of the pods in the day and they’re not moving, that’s a good thing. They’ve got pathogens. You want that,” he said.

Diamondback moths of low concern

Diamondback moths stayed relatively quiet in western Manitoba but caused some problems in the eastern part of the province in late summer. Populations are believed to have blown in on winds in late May and early June.

“They don’t overwinter well in the Canadian Prairies,” Gavloski said. “They’re just kind of getting blown in almost randomly on winds, and they get dumped wherever the winds dump them.”

Lygus bugs caused scattered economic-level infestations, primarily in the Interlake, and some fields were treated. Unlike the chewing insects on the list, lygus bugs pierce plant tissue with a beak-like mouthpart, inject enzymes and feed on the juice. They particularly target buds, flowers and young seeds.

On the positive side, Gavloski said that grasshoppers and aphids were largely non-issues across the province in 2025, with very little spraying required for either pest.

“Every year, weather drives things,” Gavloski said. “We get things that go up, we get things that go down.”

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Manitoba Agriculture experts are urging farmers to scout for pest insects early so that they have the best information when deciding if to spray.

WHY IT MATTERS: Early season pests like flea beetles can cut deep into farm profits.

Good counts are key for the farmer to know if pest populations have reached the economic threshold for that combination of insect and crop. For flea beetles, for example, 25 per cent of the canola leaf needs to be lost (averaged across 10 plants and with counts repeated at five points across the field) before the Canola Council of Canada suggests a spray pass.

Manitoba’s 2025 crop protection guide notes that spraying too early or too often wastes money and sets the stage for insecticide resistance.

Resistance is “becoming more of an issue,” Manitoba Agriculture entomologist John Gavloski said during an April 16 Crop Talk webinar. “So, we want to be careful with our use of insecticides. Be scouting early. Know your thresholds and use your products wisely.”

Producers need to be out in the field at the right time, armed with the right knowledge to identify insects, he added.

Manitoba has four main groups of cutworm that feed differently and overwinter at different life stages, all important details for making a control plan. Some types clip stems at the surface. Others, like dingy cutworms, climb plants to feed on leaves at night and retreat underground by day.

“Climbing cutworms can be tricky (to scout), because you see the feeding; you may not see the cutworm,” Gavloski said.

Farmers should dig around damaged plants to confirm what species they’re dealing with.

Size is another factor when deciding whether to spray. Once the larvae are 35-38 millimetres long, most of the damage has been done, the entomologist said. Spraying might no longer be worth it.

“If you do need to control cutworms, note that they are nocturnal, so they…hide in the day. They feed at night,” Gavloski said. “So ideally, getting the spray on as close to the evening as possible is good. That way it’s fresh when they come out and start their feeding.”

Farmer friends

Gavloski also urged farmers to be on the lookout for natural pest control.

Insects like ground beetles, rove beetles and parasitic wasps are good news for the farm, since they will feed on or lay eggs in pests.

In some cases, its the larvae that are pest-eating predators. Other species, like ground beetles and lady beetles, munch on aphids and other problem insects throughout their lives.

Bring in the sprayer

If cutworms are the problem, farmers often reach for two types of chemical control, Gavloski said: diamides and pyrethroids. While diamide-based seed treatments offer early season protection, pyrethroid foliar options may be needed if the problem persists later in the season.

For flea beetles, the goal is to keep canola ahead of damage until the plants grow out of their vulnerable stage.

“Your big challenge is getting your canola to the three- to four-leaf stage in three to four weeks,” Gavloski said.

Seed treatments wear off after around three weeks and, if crop has stalled as it has in some recent years, producers will have to turn to foliar spray.

Foliar spray has become a fact of canola growing for many farms in recent years, with tales of multiple passes being done on a single field to try and beat back the wave of flea beetles.

There is research looking into how well pyrethroids are still performing to control flea beetles, Gavloski said, but “I think what’s happening is that the flea beetles are just so numerous that they’re just re-invading the field” after the pass.

Grasshopper outlook

The grasshopper forecast for 2025 is mixed. There were fewer issues last year due to the cool, wet spring, but Gavloski warned that this year might see another surge.

“They did have some pretty good egg-laying conditions,” he said.

He encouraged farmers to take part in Manitoba Agriculture’s insect monitoring programs. Those include yearly trap counts for Bertha armyworm, diamondback moth, pea leaf weevil and cabbage seedpod weevil.

The post Watch early for insect crop pests appeared first on Manitoba Co-operator.

Gavloski couldn’t say for sure if insect damage was going to be bad this year but based on what’s transpired over the last three years, he said it depends on conditions, especially for flea beetles and canola.

“Canola growers should definitely be scouting for flea beetles. A large degree of how much damage they cause will be determined by how quickly the plants are germinating and growing through those seedling stages,” he said.

“If we get weather conditions where there is quick germination and quick seedling growth, the seed treatments might be all that we need to protect from the flea beetles. If growth seems to stall in that seedling stage, that can sometimes result in the seed treatment wearing out and people are having to spray.”

Gavloski also advised to watch for signs of cutworms in canola, wheat, sunflowers and other crops.

“A couple of years ago we had some really high levels. Things seem to be tailing off a bit, but there are probably still areas where cutworms could be economical,” he said.

Grasshoppers are another potential pest that need to be high on one’s scouting list. Gavloski noted the last few years have been “conducive for grasshopper populations to build.”

Besides the above three pests, the entomologist said there’s always a chance of the winds carrying in other pests — something that cannot be predetermined. Besides scouting for insects, he suggested farmers review the Manitoba crop pest updates.

— Glen Hallick reports for MarketsFarm from Winnipeg.

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The company had said last November it wasn’t yet sure those products would be available this year under an approaching deadline following a 2021 re-evaluation of lambda-cy by Health Canada’s Pest Management Regulatory Agency (PMRA).

The PMRA’s re-evaluation decision cancelled the product’s uses on all feed crops, condiment-type mustard, bulb vegetables, lettuce and some oilseeds effective 24 months from its decision date, thus setting a deadline of April 29, 2023.

The list of affected oilseed crops does not include canola/rapeseed, flax or oilseed mustard — but the ruling would prohibit those crops’ use as livestock feed.

Adama said Wednesday its decision to relabel the products “comes after several months of consulting with retailers, farmers and industry organizations on the implications” of the PMRA re-evaluation.

“After a great deal of discussion and consideration, we have confidence in our retail partners to provide good advice to growers and we trust growers themselves to use the product responsibly and within permitted guidelines,” Adama Canada general manager Cornie Thiessen said in a release.

“The bottom line for growers is to read the labeling guidelines carefully. Talk to your full-service input retailer and to your crop buyers so you can make an informed decision about if and when to apply the product.”

Adama had said in November the cancellation of lambda-cy’s use on crops destined for feed was especially raising red flags for farmers, who “have questioned whether it is feasible to use the product at all considering how difficult it is to trace where crops will be used after they leave the farm.”

READ MORE:

• How to manage without lambda-cyhalothrin in 2023
• Farmers discuss how lambda-cyhalothrin regulation changes will affect them in 2023
• Insecticide restriction pushes growers to older chemistries

Lambda-cy is a Group 3 synthetic pyrethroid contact insecticide used to control a broad range of pests at their small larvae nymph and adult stages.

Other products affected by the PMRA’s ruling include Syngenta’s insecticides Matador, Voliam Xpress, Endigo, Warrior and Demand CS, Intervet Canada’s Saber pour-on and ear tag products and Sharda Cropchem’s Labamba insecticide.

Syngenta, like Adama, launched a product recall to “amend existing labels” ahead of the April 29, 2023 deadline.

However, Syngenta also said in November it has decided not to sell lambda-cy products at all in Western Canada in 2023, though it will continue to sell Matador in “horticultural markets” in Eastern Canada.

Syngenta said via email that decision was meant “to avoid any confusion and to support 2023 business planning with our customers.”

It also said it had filed a submission to PMRA seeking reinstatement of as many livestock feed crop uses as possible and “will continue to support this submission until completed.”

Provincial agriculture ministers from Saskatchewan and Alberta last month also called for PMRA to reconsider its re-evaluation decision, saying it “leaves farmers with one fewer tool to address potentially destructive pests.”

Grasshoppers, in particular, are likely to be a significant concern again this year following “continued drought” in parts of those provinces, ministers David Marit and Nate Horner said in a statement.

The PMRA decision “could also mean the inability for canola producers to sell their products as livestock feed, which could impact availability for cattle and lamb producers,” the ministers said.

Horner and Marit said they have written to the federal health and agriculture ministers urging them to encourage the PMRA to reconsider.

“It is possible for the PMRA to enact an emergency reinstatement of the product’s use to ensure our farmers can use it for the coming growing season and give it time to make a more informed decision, but we would need that immediately,” the ministers said.

“With extreme flea beetle pressure, hotspots for grasshoppers and cutworms across the Prairies and forecasted outbreaks, the lambda-cyhalothrin decision could severely impact our yields, our livelihoods, feedstocks and food prices,” Alberta Canola chair Roger Chevraux and SaskCanola chair Keith Fournier said in the provinces’ joint release on Feb. 24.

“Lambda-cyhalothrin has a significant market share, and it will strain farmers to source alternative products.”

Noting the U.S. Environmental Protection Agency (EPA) has not imposed similar restrictions on lambda-cy use, the canola grower commission chairs said PMRA “needs to base its decisions on sound science and be aligned with our largest trading partner.” — Glacier FarmMedia Network

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