Crops should be monitored at least twice a week during the growing season. An insecticide application is recommended when larvae counts reach this point. An action threshold for canola or mustard in the early flowering stage has not been established. Pest Management Natural controls Natural factors can have a profound impact on diamondback moth populations. Weather Cool, windy weather reduces adult activity and females often die before they lay all their eggs.
Heavy rainfall can drown small larvae and reduce numbers by more than half.
Humid conditions within the crop following a rainfall can promote the spread of fatal fungal diseases throughout the diamondback moth population. Biological factors Diamondback moths are affected by diseases, parasites and predators. Entomophthorales fungi cause natural disease outbreaks in diamondback populations. These outbreaks usually occur late in the growing season when populations are high. The rate of infection of diamondback moth larvae can be high enough to limit the development of additional generations late in the season.