Grass Sawfly Showing Up Again

Grass Sawfly Larva (T. Baute, OMAFRA)

I was hoping this was a one time pest that showed up last year.  But there have been some wheat fields in the Highgate/Muirkirk to Kerwood areas that are seeing grass sawfly feeding.  It is easier to identify grass sawfly since they feed during the day.  They also have a characteristic feeding habit of clipping the wheat stems, sometimes in sections, leaving a small pile of short straws and heads on the ground.

What is odd is that the experts who I was in contact with last year said this pest only really becomes a problem when you experience warmer than usual April temperatures.  That is when the sawfly adult lays its eggs.  Do you remember April being warm this year because I certainly don’t?

The good news is that experience from last year taught us that this pest really doesn’t feed for that long.  By the time you see the damage it is already at least half way through its feeding period.  You are really only looking for a 7 to 10 day window of feeding so assessing threshold and implementing control, if needed, has to take place in a short time frame.  Also, the infestations tend to be very patchy in fields, often along the fields edge so spraying the entire field may not be economical.  Also keep in mind that you could have both armyworm and grass sawfly active in the same field and may need to assess the impact of both while making your management decisions.  Armyworm can also clip heads so don’t blame the wrong pest for the damage.

More pictures and threshold is available in previous blog entries that I have written at: