Red turnip beetle infestations originate in stubble fields previously seeded to canola, rapeseed or mustard or in other fields containing heavy stands of weeds of the mustard family, which have not been cultivated in the fall or early the following spring. For this reason, avoid the practice of underseeding canola, rapeseed, or mustard with forages. Cultivation is an extremely effective means of reducing red turnip beetle eggs, larvae, and pupae. Cultivation after harvest buries the eggs and when they hatch, the larvae are unable to burrow out of the soil. Fall cultivation may cause 75-100 per cent mortality of newly hatched larvae the following spring.
Cultivation also controls the larvae by destroying hosts plants.
When the host plants die, most larvae starve to death, for they are incapable of travelling very far for food. A similar situation occurs when herbicides are applied to control volunteer canola, rapeseed, mustard, or weeds of the mustard family while the insect is still in the larval stage. When adult beetles invade newly-seeded canola, rapeseed and mustard fields in June, it may be necessary to use chemical insecticides to control them. The affected fields should be examined carefully, to determine the density of beetles and whether the beetles are causing economic damage. Since they usually walk into fields from the margins and are concentrated in a moving front, insecticide application can usually be confined to plants along the field margins.