Although wheat is the principle host plant, Hessian flies may also be found on rye, barley, and some wild grasses. Damage - In the midwest, Hessian flies are one of the most destructive pests of wheat. The maggots burrow between the leaf sheath and the stem and extract juices from the plant. Fall-infested wheat usually dies during the winter. Spring-infested wheat produces grain but usually lodges before harvest.
Economic infestations are uncommon in North Carolina largely due to proper planting date selection.
Typically, Hessian flies complete two generations per year, a spring brood and a fall brood, although as many as six generations a year have been reported. The pupae overwinter within puparia, the hardened skins of the last instar larvae. Maggots hatch from the eggs in 3 to 7 days, crawl down the leaves, and feed at the crown or joints along the stem. The maggots develop through three instars over a 25 to 30 day period, enter the flaxseed stage before harvest, and pass the summer in the stubble. In late August or September, second generation flies emerge and deposit eggs on volunteer wheat or early-sown winter wheat.