CANOLA QUIZ – This Week in Insects

Four questions on insect observations in canola fields this week in Western Canada.


While scouting this time of year, you may find tiny holes in pods. These are quite likely exit holes from cabbage seedpod weevil larvae. Check a number of pods to see how many have exit holes. If no more than _____ per cent of pods have exit holes, the spray worked. If you didn’t spray, this amount of exit holes would suggest you made the right decision. (Fill in the blank.)

Lygus bugs are no longer a threat to a canola crop once pods become leathery and seeds inside are firm enough to roll between thumb and finger without squishing. Why does the threat end at this stage?

Next generation flea beetle adults are commonly seen on canola later in the summer (or mid summer in 2021). They are not usually an economic threat unless they're widespread and at high numbers. Numbers higher than ____ flea beetles per plant may be necessary to cause significant yield reductions. (Fill in the blank.)
4. Lygus, grasshoppers and flea beetles are all in the same field eating on pods. None is over thresholds, but together they probably exceed the economic threshold for an insecticide application. Would a spray be allowed?