Wheat Midge Frequently Asked Questions

What are these little orange mosquito- like bugs in my wheat?
These small bugs that are about half the size of a mosquito and bright orange are probably wheat midge. They will lay eggs in the wheat head and the larvae will then feed on the wheat kernels.
Lauxanids are commonly confused with wheat midge, but the Lauxanid is a little bigger and not as orange.

What kind of damage can the wheat midge do to my crop?
The wheat midge larvae can decrease the yield of your crop. One midge per 4-5 wheat heads can decrease yield around 15 percent. They can also reduce the grade of your wheat. If there is more than one midge per 8-10 wheat heads there is a risk of a reduced grade. The Canadian Grain Commission limits midge damage in No. 1 CWRS wheat to 2% and 8% in No.2. In durum the tolerances are similar.

When should I be scouting for wheat midge?
Adults appear in late June and early July. Scouting of your wheat field should be done regularly between heading and flowering. Scout in the evenings, from about 8 - 10 pm, when the temperature is around 15 degrees Celsius and there is no or very light winds. Also, scout four or five places in the field for a more accurate count.

What are the thresholds for wheat midge?
One adult midge per four or five wheat heads is usually enough to warrant control measures.

What can I use to control wheat Midge?
Cygon™, Lagon™, Lorsban 4E™, Nufos™ and Pyrinex™ are all registered for use on wheat midge in wheat. Check the label for any other restrictions regarding the chemicals. For example Cygon™ and Lagon™ do not control the eggs, just the adults. Also, watch the stage of the crop, as certain chemicals have to be applied at specific times for good control. Check the label for application timing.

Considerations for Control
Late evening or early morning are the best times to control the adults, as the females are most active in cool nighttime temperatures (but above 15 degrees Celsius or 59 degrees Fahrenheit) and when the wind is less than 10 km/hr (6 mph). Also, good coverage is critical for control if your chemical controls eggs as well, so make sure your water volume is adequate. Optimal control happens when 70% of the crop is in the heading to flower stage. If 30-60% of the crop is flowering then it needs to be sprayed immediately to have good control on the wheat midge. If 80% of the crop is flowering then control is not recommended as the window has passed and the midge damage has already started. Spraying therefore should be done early to protect the main stem and first tiller, as this is where most of the yield potential of the crop is.

Wheat Midge Fact Sheet
Insecticide Selector
Canadian Grain Commission (450 KB) - Official Grain Grading Guide for Wheat (see Tables on 4-32 onward for Sawfly/midge damage levels).

Prepared by Lisa Adam, Ag-Info Centre, Alberta Agriculture and Rural Development

For more information about the content of this document, contact Ag-Info Centre.
This information published to the web on July 15, 2003.
Last Reviewed/Revised on April 22, 2008.