These larvae, called maggots, feed in the onion bulbs. They can kill young plants or cause misshapen bulbs and rotting. Growers use Integrated Pest Management to control this pest. If onion maggots are suspected, growers can monitor for the flies using white sticky traps which have proven effective in detecting the onion maggot fly. Only if a certain threshold level is reached, as determined through monitoring, do growers use insecticide sprays.
Growers also face the challenge of competition from Europe.