Cabbage Root Maggot

Root Maggots are consistently found in most canola fields in the County. Populations are generally low and rarely occur in yield-reducing numbers. The adult phase of the cycle is a fly which lays eggs in the spring and these eggs hatch as maggots. The maggots then migrate to the root system of canola plants and begin feeding. The resulting severity of the damage is related to the amount of maggots present. There is always a chance of a loss in yield due to an abundance of adults present and amount of eggs laid.

What To Look For

Pupae Maggot
Root damage Fly
Root Maggot life cycle


There are no control measures for Cabbage Root Maggot available due to the nature of their cycle. Adult flies lay eggs over a lengthy period of time thereby making insecticide application unfeasible. There are however, some cultural practices which can help to reduce the impact of the damage:

  • Plant the canola crop with seed of high germination and vigour
  • Increase seeding rate if a problem is suspected
  • Widen row spacing
  • Assure good fertility with proper balance of nutrients for canola production