Western Kansas on Alert for Wheat Stem Sawfly

The content for this blog came from my interview with Jeanne Falk Jones, multi-county agronomy

specialist.

While much of Kansas has been battling the effects of wheat streak mosaic virus this harvest season, growers in western Kansas are also keeping a close eye on another potential threat: the wheat stem sawfly. This pest, which has caused significant damage in neighboring Colorado and Nebraska, could be the next challenge Kansas wheat producers face.

Jeanne Falk Jones, a multi-county agronomy specialist based in northwestern Kansas, explains what farmers need to watch for. “This is a flying insect—though not a strong flyer—that lays eggs inside the wheat stem,” she said. “The larvae feed inside the stem and weaken it from within. Around harvest time, the plant often falls over, making it difficult or even impossible to harvest.”

The larva essentially cuts off the plant from the inside, often just an inch above the ground, resulting in a clean break. This damage typically becomes visible right when the crop is ready to be harvested, compounding the frustration for farmers.

Controlling the wheat stem sawfly is especially challenging due to its short and staggered life cycle. “The adult females only live about seven to ten days,” Falk Jones said. “But they don’t all emerge at once—they can appear over a four- to five-week period. That makes timing an insecticide application extremely difficult.”

Insecticides are largely ineffective against this pest, and researchers from Colorado State University and other institutions are actively seeking alternative management solutions.

One promising strategy is the use of wheat varieties with solid or semi-solid stems. “These types of wheat have thicker stem walls,” said Falk Jones. “That makes it much harder for the female sawfly to lay her eggs inside, helping to reduce infestation rates.”

As the threat continues to evolve, farmers in western Kansas are advised to stay vigilant and consider planting resistant varieties as part of their long-term management strategy.