Crucifer flea beetle biology & life cycle
In Western Canada there are two primary species of flea beetles to scout for: the crucifer flea beetle, which is uniformly blue-black and shiny; and the striped flea beetle, which has two horizontal yellow stripes running the length of its otherwise black body. The crucifer flea beetle is abundant across all canola growing regions, while the striped flea beetle is now common in in both the black and dark brown soil zones. They are both small, only 2.5mm long, and hop away when disturbed, making them hard to see and harder to count. It’s one reason flea beetle control programs usually begin with preventative measures, such as seed treatments that include an insecticide.
Adults overwinter in leaf litter along shelterbelts or fencerows. They emerge in mid-April to late May and begin feeding on early emerging crucifers (weeds or volunteers). Adults move to emerging cruciferous crops and feed on cotyledons and first leaves. Females lay eggs at the soil surface and larvae feed on root material of the developing plant. An earthen cell is formed for pupation. Adults emerge from the soil and feed on leaves or pods of hosts and then overwinter. One generation is produced each year. Overwintered adults cause the most damage to young canola seedlings in the spring. Adults chew holes in the cotyledons or epidermis of young leaves.
