Diamondback Moth

The Diamondback Moth is a less common pest in the County however they are found here, generally in well-below threshold numbers, in most canola fields in any given year. The moths are mainly blown in on southeast winds from Texas and California. There is research showing the insects may overwinter in Western Canada if the conditions are favourable for them. The larvae, which hatch in early July, are voracious feeders and in large numbers, can cause a great deal of damage in a canola crop. They feed on leaves for the first stages of their lives and then move upward to the flowers which is where the most damage occurs. This pest is one that we monitor here in the County through the use of pheromone traps early in the spring.

What To Look For

Larvae and pupae Larvae feeding
Adult moth Adult moth

Prevention

Canola is a member of the Brassica family which also includes cabbage, stinkweed, lambs quarters, etc. All of these plants are hosts to the Diamondback Moth. There are steps to take that may reduce or eliminate the threat of these insects in canola crops:

  • Control all host plants including volunteer canola
  • Check Alberta Agriculture website for local insect forecasts
  • Scout fields from early May and throughout the growing season
  • Consider recommended insecticide only when threshold of larvae (20-30 per sq metre) is reached to minimize impact on beneficial insects