Canola Watch quiz – bertha armyworm

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

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

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

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

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?

6. Economic thresholds for bertha armyworm depend on canola prices and insecticide application costs. If canola is $10 per bushel and total cost of insecticide (product plus water and application) is $12 per acre, the threshold would be ______ larvae per square metre of crop.