The loss of individual kernels will lower yield, whereas damaged kernels will reduce the grade of the harvested wheat. Standards established by the Canadian Grain Commission limit midge damage in No. 1 CWRS and No. 2 CWRS to two per cent and eight per cent respectively before grade is affected. Monitoring Recent studies indicate that wheat heads are more susceptible to damage when egg laying occurs during heading. Kernel damage is reduced by 20 to 25 fold between heading and early flowering. Therefore, fields should be inspected daily from the time wheat heads emerge from the boot leaf until anthers are visible on the heads.
Glenlea wheat remains very susceptible to damage after flowering.
Monitor this variety carefully throughout the heading and flowering stages. Midge populations can be estimated by counting the number of adults present on four or five wheat heads. One midge adult for each four or five heads usually warrants control measures. Inspect the field in at least three or four locations. Midge densities and plant growth stages at the edge and centre of fields may be very different.