29 May Species Survey in the Special Areas
Article by Amanda Jorgensen, M.Sc., ATT
Insect Management Specialist, Alberta Agriculture & Irrigation
Warm conditions last fall mean that cutworms and grasshoppers had an ideal egg laying period. Even with a cool, slow spring, there still is risk from these species.
Grasshoppers
Grasshopper numbers were high in Special Area #4 and in parts of Special Area #2 nearby. Remember two important things about the survey: it counts all adults (not just pests!), and it provides a regional outlook. Individual fields will vary in risk.
Start scouting now; grasshoppers are harder to find but easiest to control when they are small. Small grasshoppers can be confused with leafhoppers, so use a sweepnet to confirm grasshopper presence. But remember to count the number of grasshoppers per metre square when using the economic thresholds.
Only 5 of our 85 grasshopper species are pests. Any grasshoppers that are adults before July, that make any sort of noise, and most brightly colored grasshoppers are not pests and do not require control.
If grasshopper numbers in rangeland warrant chemical control, applying control every other pass is just as effective as spraying the whole field.
| Thresholds in ditch | Thresholds in field | |
| Cereals | 50-75 nymphs or 21-40 adults /m2 | 30-45 nymphs or 10-12 adults /m2 |
| Canola | 50-72 nymphs or 24-50 adults /m2 | 30-45 nymphs or 12-14 adults /m2 |
| Lentil, flax | None available | 6-9 nymphs or 2 adults /m2 |
| Pasture, range | None available | 45-60 nymphs or 15-20 adults /m2 |
Alfalfa Weevil
Alfalfa hay and seed producers should scout for alfalfa weevil in June. Scouting and following economic thresholds is important for protecting natural enemies and slowing resistance development. In hay, cutting the first growth early can reduce alfalfa weevil populations.
Deltamethrin resistance has been observed in the Rosemary area, so producers in that region should avoid products containing deltamethrin.
| Thresholds in alfalfa hay | Thresholds in alfalfa seed |
| 25-50% of leaves on upper third damaged | 20-30 third or fourth instar larvae per 180° sweep |
| 50-70% of terminals damaged | 35-50% of tips showing damage |
| 3 larvae per stem (2 at 40 cm, 1 at 30 cm plant height) |
Flea Beetles
There were some higher numbers of flea beetles in the fall in the Big Stone area, but all canola producers should watch for flea beetle damage until the 4-leaf stage.
Bertha armyworm
Bertha armyworm numbers increased in 2025. Watch the live map this season to get an early warning on 2026 numbers.
Cabbage seedpod weevil
With a mild winter, expect most hibernating cabbage seedpod weevil to have survived the winter. Watch areas closely that had high numbers of weevils in the fall. Sweep canola that is first to flower, even in areas that don’t typically have cabbage seedpod weevil issues.
Wheat stem sawfly
Wheat stem sawfly cutting was lower in 2026, but growers near the border with the M.D. of Acadia still saw cutting. Leave at least 6 inches of crop stubble to preserve natural enemies and lower sawfly numbers.