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Identifying Hessian Fly and Its Damage The damage from Hessian Fly may be overlooked as the insect culprit is not easily observed. Wheat infested in the fall is stunted, extra dark green, and the leaves may stand more erect then normal because the infested stems become thickened. The central growing shoot is often missing and small greenish white maggots (headless) can be found beneath the sheaths of the leaves. Heavily damaged plants die during the winter and surviving plants in the spring will have the fall symptoms. In the winter and early summer the pupa "flaxseed" stage will be found under the leaf sheath. See seasonal development chart. The adult fly is a small black fly the resembles a mosquito but does not have the long feeding tube that mosquitoes use to suck blood. The fly is about 1/8 inch long and may be found a long distance from the infested field that it emerged from. The Hessian fly attacks wheat, barley and rye, but wheat is its favorite food. Oats are not known to be a host and it has only been collected on rare occasions from wild grasses or lesser small grains.

Hessian Fly Images larva, pupa, flaxseed flaxseeds on wheat stem larvae beneath leaf sheath "flaxseed", pupa adult female adult male map of safe-sowing dates for wheat growing sections of the U.S. seasonal development: April, May, June seasonal development: July, August, September seasonal development: October, November, December seasonal development: January, February, March