Adults overwinter in soil beneath leaf litter in shelter belts and roadside ditches and emerge from these sites in spring when soil temperatures warm to approximately 15 ºC. Adult weevils are ash-grey and approximately 3 to 4 mm long. They have a prominent curved snout that is typical of most weevils. Adults can be found on early flowering hosts (wild mustard, flixweed, hoary cress, stinkweed, and volunteer canola). Weevils move to canola fields when the crop is in the bud to early flower stage and feed on pollen and buds, causing the flowers to die.
The risk of infestation in canola can be predicted based on the size of the adult population. The recommended time to sweep-net sample in canola is when 10 to 20% of plants are flowering, which happens about 1 week after the onset of flowering.
