They are cabbage seedpod weevils and in two years have spread from Lethbridge in southern Alberta north about 250 kilometres and about the same distance east. Carcamo is working with other Agriculture Canada and provincial insect specialists to try to find ways to slow the pest's spread. They also want an economical control method for where it has settled. The first line of defence is sanitation. Harvesters should clean equipment, trucks and other machinery that move across the Prairies.
Crop damage can occur at several stages.
At flowering, invading adults feed on the buds, causing bud-blasting and reduced yield potential in dry years. At seed development, each larva eats about five seeds before leaving the pod, causing holes where disease can set in and further damage the plant. Carcamo is developing a control strategy based on the weevil's tendency to attack a crop when it is flowering. He has started a project looking at luring the weevil into a trap crop that will be sprayed, lessening the need to spray the whole field. We plant a border of say 20 metres of Polish canola all the way around a field of Argentine canola.