Wheat stem sawfly – Survey and maps

The area affected by sawfly cutting damage in 2025 has continued to decrease in Alberta. We are still seeing moderate to high cutting percentages in the traditional sawfly areas. The random nature of the survey means that individual fields may have higher wheat stem sawfly populations than are indicated in the survey map.

Producers are aware of sawfly in their fields. Cutting levels of 10 to 15% or higher in the previous crop year indicate the need to consider planting non-host broad-leaf crops, oats, or solid-stem varieties to reduce sawfly losses. The risk in the traditional wheat stem sawfly areas still continues in 2026.

Methodology

The wheat stem sawfly survey is an after-harvest survey completed in the fall of 2025. The population map is based on 92 fields in 22 municipalities across southern Alberta and the municipalities along the Saskatchewan – Alberta border as far north as Bodo (MD of Provost). 

In each field, the number of stems cut by wheat stem sawfly and the number of uncut stems is counted in one metre of stubble in 4 locations along the headland. The percentage of cut stems is then determined.

Field locations denoted by a black dot had zero sawfly found in the survey. While the overall area impacted by sawfly cutting decreased in 2025, the severity of damage increased slightly in Forty Mile and Warner Counties.

The percentage of stems cut by sawfly gives an indication of the number of reproductive adult sawflies that will emerge in late June through early July. Winter conditions have very little impact on sawfly populations and a high proportion of wheat stems cut in the fall will produce adults.