Control Options Environmental and biological Cool temperatures and wet soil conditions at the time of egg laying are the main factors influencing the levels of cabbage maggot. Cabbage maggot infestations are more severe following a cool, wet spring. On the other hand, populations are generally lower in hot, dry years. There are a number of natural biological control agents present on the Prairies, including a fungus that attacks adult flies, and a parasitic wasp and parasitic beetle that each attack the pupae. In addition, vast numbers of maggot eggs are eaten by rove beetles.
Insecticides Controlling the maggot in canola is difficult at best.
In-furrow application of granular insecticides with the seed will give some first generation maggot control. However, there are currently no pesticides available for control of maggot infestations in canola or mustard later in the season. For high value cruciferous vegetable crops such as cabbage and broccoli, root damage and crop losses can be reduced by applying a soil insecticide drench at the time of transplanting and at two week intervals until the end of June, and again from late July to mid-August. Refer to specific pesticide labels for registered crops and rates of application. Cultural controls Cultural practices can have a considerable impact on cabbage maggot populations.