QUIZ – Bertha armyworm scouting

Jay Whetter July 22, 2026

Six questions to help you with bertha armyworm scouting, including where, when and how to count, and how many worms is too many.

1. The following are all features of bertha armyworm, but which one best distinguishes bertha armyworm from other worms you might find in canola?

Yellow/orange stripe down each side

Worm length of 1” to 1.5”

Green colour

Black/brown colour

Feeds high in the canopy

2. Bertha armyworms will all eventually turn dark brown or black.

True

False

3. Where would you look for bertha armyworms during the day?

On the pods

The underside of leaves

On the ground and under debris

Underground

4. Can you determine if a field should have economic levels of larvae based on counts from a pheromone-baited trap?

Yes

5. If a field has levels of bertha armyworm larvae that are above the economic threshold, is it likely that all nearby fields will also have high levels of larvae?

Yes

6. Economic thresholds for bertha armyworm depend on canola prices and insecticide application costs. If canola is $16 per bushel and total cost of insecticide (product plus water and application) is $20 per acre, the threshold would be ______ larvae per square metre of crop.

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