Diamondback Moth Monitoring Program in Manitoba - 2021


Diamondback moth does not overwinter well in the Canadian prairie provinces, but large numbers can potentially blow in. If conditions are favorable for their survival and reproduction when they arrive, and if natural enemies do not limit population establishment, populations can increase.

Pheromone-baited traps (Fig. 1), which attract the male moths, are established for a 6-8 week period from early-May until late-June to detect the arrival of populations of diamondback moth early in the season. The cumulative counts from the traps can not predict what levels of larvae will be, but can be used to determine regions of the province where increased attention for diamondback moth is recommended when scouting fields.

Fig. 1. Trap for diamondback moth                                 Fig. 2. Diamondback moth on insert of trap

 Summary (as of July 12, 2021)

Pheromone-baited traps for adult moths have been set up at 98 locations in Manitoba in 2021.
  • Trap counts were generally low until late-May. Since then some moderate counts have occurred in traps in the Northwest, Central, Interlake and Eastern regions.
  • Only 65 traps have caught any diamondback moths.

The highest cumulative trap count so far is 171 from a trap in the Interlake region. In spite of some strong winds from the South, a lot of traps still have low numbers, with a few traps showing moderate counts.


Table 1. Highest cumulative trap counts per agricultural region in Manitoba over the trapping period (April 25 to July 12, 2021) 


Location Count
  The Pas 155
  Bowsman 68
  Makaroff 52
  Grandview 39
  Bowsman 38
  Minto 48
  Carberry 36
  Minto/Boissevain 23
  Fairfax 17
  Douglas, Brandon, Lyleton 6
  Haywood 68
  Edwin 57
  Altona 35
  Starbuck 21
  Culross 21
  Ninga 17
  Stead 106
  Beausejour 43
  Hadashville 38
  River Hills 29
  Tourond 17
  Selkirk 171
  Clandeboye 66
  Arborg 52
  Vidir 50
  Stonewall 16


Guidelines for monitoring larvae of diamondback moth can be found at:

                                            Fig. 3. Diamondback moth pupa (left) and larva (right).