Hessian Fly

— Written By and last updated by Patricia Burch

Will Hessian fly be an issue in wheat this year? They very well could be. This may or may not mean anything for Sampson County; however, I just wanted to get you thinking about it if you have planted wheat this season.

Hessian fly can cause damage to young tillers by larvae feeding. So, what do you need to do? First and foremost, if your wheat seed was purchased with an insecticide seed treatment, then you most likely will be okay. Back several years ago, an NC State University Graduate student conducted a study about Hessian fly feeding damage in the fall and the insecticide seed treatments alone were enough protection for the tillers. Scout your wheat fields for potential invaders.

At this time, the Hessian fly is in the pupal (resting) stage. The pupa is a dark brown case that resembles flax seed. If present, the pupa will be found between the sheath and the stem near the base of the wheat plant. You should be scouting your fields now to determine whether or not your wheat field is infested.

Conditions that may have an influence on these pests include: A Hessian fly susceptible wheat variety, planting seed without an insecticidal treatment, wheat/wheat rotation (especially no-till), wheat emerged before November, and wheat fields planted near last year’s wheat fields.

If a spring infestation of Hessian fly is present in your wheat field, tillering will be poor, plants will look yellow and unthrifty, have small heads, will be noticeably shorter, and lodging will be evident. If any of these symptoms are present and you have gone out and found Hessian fly pupa or larvae, it might benefit you to apply an insecticide. In the spring, apply an insecticide as the pupa hatch and flies emerge.

The flies typically emerge when temperatures warm in mid-to-late March. They are small, long-legged, and look like a small mosquito. The fly is a weak flyer and lives only about 2-3 days. Flies will deposit yellow-orange eggs singly or end to end between the veins on the upper surfaces of young wheat leaves. The eggs will hatch within a few days and the tiny maggots will migrate to stem joints where they feed for 4-6 weeks. The maggot is about ¼-inch long when fully grown. Maggot feeding usually results in weakened stems and small, poorly filled grain heads with low-quality kernels. Weakened stems may result in lodging of your wheat plant.