Written by: Abigail Wiesner, Acting Canola and Edible Bean Specialist

Canola flower midge adult. (Jonathon Williams; AAFC-Saskatoon)

A new pest of canola has been identified in Ontario (2021) after being found in Western Canada in 2016. Canola flower midge (CFM, Contarinia brassicola) is a small midge species in the same genus as swede midge, with similarly small larvae that cause damage to canola flowers.

Three examples of damage caused by the canola flower midge on the left compared to three examples of damage caused by swede midge on the right. (Jonathon Williams; AAFC-Saskatoon)

Canola flower midge eggs are laid in unopened flower clusters. After hatching, the larvae feed within the flower. This creates a bottle shaped gall, distinct from the caper-like galls created by swede midge (Fig. 2). While signs of damage are the easiest way to identify CFM presence, the distinct bottle shaped galls have yet to be seen here in Ontario. Damaged flowers fail to bloom or set pods, leading to yield losses. However, the extent of economic damage is unknown, but recent work suggests its less than swede midge.

In Ontario, research is being conducted by Dr. Rebecca Hallett’s lab at the University of Guelph. Research aims to define the distribution of CFM in Ontario as well as the potential economic threat. Growers are encouraged to reach out to participate in research and report any CFM damage to Angela Gradish (agradish@uoguelph.ca).

Example of damage to flower buds on canola plant caused by canola flower midge. (Dr. Boyd Mori; University of Alberta)