Auburn University Extension entomologist Kathy Flanders is worried about the threat of Hessian fly on wheat this year, and the main source of her worry is a long-forgotten storm from 2011.

“Many growers remember we had high populations of Hessian fly in 2008 and 2009, and we had a lot of damage from this insect,” said Flanders at the recent Central Alabama Corn Production Meeting in Autaugaville.

“I’m worried because of Tropical Storm Lee,” she says. “The Hessian fly spends its summers in wheat stubble, such as in double-cropped soybeans. Along about the end of August and the first part of September, the first generation of this pest will come out. If it’s really dry at that time, it may interfere and you won’t have as many Hessian fly for the first generation.

“But Tropical Storm Lee came through Alabama last year just in time to wet the soils across the state, so if there were any pupae down there that were summering in soil, in the stubble itself, or just under the soil surface, they have a good chance of coming out.

“Then they’ll be looking for volunteer wheat, wild hosts, early planted wheat, or wildlife plots on which to reproduce. They’ll probably have time for at least a generation before they try and fly on to commercial wheat crops.”

The Hessian fly looks like a small mosquito, says Flanders, and when you’re scouting the fields, it’s hard to tell the difference between it and a gnat. “The larvae are what cause the damage. The eggs are laid on the leaves, and the maggots hatch out and make their way down the base of the plants, hiding out along the leaf sheaves and doing their feeding. We have several generations each year of this pest,” she says.

If you planted wheat early, Hessian fly might be in the field in the form of the larvae or pupae, she says. However, the first good killing frost usually kills off any adults that still might be hanging around.

(A big reason to worry about the Hessian fly in the Southeast is that varietal resistance seems to be breaking down. For an in-depth look at that situation, see http://southeastfarmpress.com/grains/hessian-fly-resistance-threat-southeast-wheat and http://southeastfarmpress.com/grains/wheat-resistance-genes-failing-against-hessian-fly.)

How do you know if you have an early season problem with Hessian fly? Flanders says when the maggots come out during the early part of the season, when the wheat is coming up, they lay eggs on the leaf. They then make their way down to the base of the plant, which is underneath the ground.

“When it starts feeding, it stunts the plants, and plants don’t emerge normally. If only half of the leaf blade is coming from the ground, it could be a sign that you have a problem. Also, if you have skips in your stand, it could be a sign,” she says.