Canola School: Flea Beetles Bite, Cutworms Hide — What Growers Need to Know

Why It Matters

Effective early‑season management of cutworms and flea beetles can safeguard seedling establishment, directly influencing canola yield and profitability for Canadian producers.

Key Takeaways

• Early-season scouting essential for both cutworms and flea beetles.
• Flea beetles cause 25% leaf damage threshold before spraying.
• Cutworms appear as bare patches; monitor nocturnal activity.
• Seed treatments reduce risk; consider add‑on options for high pressure.
• Use regional pest history to decide on pre‑emptive treatments.

Summary

The Real Agriculture “Canola School” video, sponsored by BSF Canada and Invigor Hybrid, features University of Alberta associate professor Dr. Boyd discussing two early‑season canola pests—cutworms and flea beetles—and what growers should know as seedlings emerge.

Dr. Boyd explains that both insects appear soon after emergence, but flea beetles are widespread while cutworms are patchy. He outlines scouting tactics: look for characteristic shot‑hole feeding and a 25 % leaf‑damage threshold for flea beetles, and search for bare soil patches and nocturnal larvae for cutworms. Seed treatments containing neonicotinoids are standard; in fields with historic pressure, add‑on insecticide treatments are recommended, and foliar sprays become necessary once thresholds are reached.

“If you’re hitting that 25 % action threshold, a foliar spray is required,” he warns, and adds that cutworms can be identified by their C‑shaped curl in the hand. He also notes the presence of parasitic wasps that target adult flea beetles—an interesting but insufficient natural control—and that over ten cutworm species can affect Alberta canola.

The discussion underscores that pest pressure cannot be precisely predicted, so growers must rely on regional history and proactive scouting to decide on seed‑treatment packages. Timely identification and treatment can prevent seedling loss, protect yields, and reduce reliance on reactive foliar applications.

Original Description

Warm conditions may still feel a long way off, but early-season insect pressure is never far behind for canola growers.

In this episode of RealAgriculture’s Canola School, University of Alberta associate professor Dr. Boyd Mori joins Amber Bell to speak about two key early threats: cutworms and flea beetles.

Both pests target canola at emergence, but their behaviour in the field differs. “Both cutworms and flea beetles are generally early season pests… as soon as our seedlings start to emerge… that’s generally when we have to deal with both,” says Mori, noting that while flea beetles tend to be widespread, cutworms are typically patchy and harder to predict.

That difference shapes scouting strategies. Flea beetle damage is easier to spot through the characteristic “shot hole” feeding on cotyledons and early leaves, with an established action threshold of 25 per cent leaf area loss. Cutworms, on the other hand, require more investigative work, as larvae feed below the surface and are often only detected after bare patches appear.

Management also varies. Most canola acres are protected from flea beetles through neonicotinoid seed treatments, with additional products or foliar sprays considered when pressure exceeds thresholds. Cutworm control is more reactive, relying on field history, scouting, and in-season foliar applications where needed.

Because both pests are unpredictable, past experience plays a key role in planning. “We really don’t have good ways to predict them… it’s really based off of kind of the grower and the agronomist experience in that region,” Mori explains.

Ultimately, the message is consistent: get out of the truck and into the field. Regular, boots-on-the-ground scouting remains the most reliable way to protect yield potential during those critical early growth stages.

Website: https://www.realagriculture.com/

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