MANHATTAN, Kan. - In some Kansas alfalfa fields, alfalfa weevil eggs are hatching, and small larvae are feeding on the new plant growth, a Kansas State University scientist said.

K-State Research and Extension entomologist Jeff Whitworth has been fielding producers' reports about the insects. Samples taken from fields in mid-March confirmed the activity.

"This is somewhat earlier than normal," Whitworth said, "and is probably due to eggs laid last fall or early winter."

Dry conditions through much of the winter have taken a toll on the state's alfalfa crop. Rain and snow across much of the state the week of March 19 may not have been enough to help the struggling crop, he said.

Producers would need to inspect alfalfa terminals closely now to find evidence of larval feeding, because the leaves probably show only pinhole-size damage. As the larvae grow and feeding progresses, however, the damage will become more apparent, Whitworth said.

When the weather warms back into the 50-plus degree range, alfalfa growers should monitor their fields, for the surviving larvae will resume feeding and additional eggs are likely to hatch. Potentially, that could create a situation in which weevil feeding continues for an extended period of time, he said.

"We do not recommend treating alfalfa weevils until the weather is projected to be above 50 degrees for a few days, as freezing temperatures with freezing precipitation may impact the plants and/or the alfalfa weevil populations. What you find prior to cold weather may be totally changed after the cold weather," the entomologist said.

"Be aware, however, weevils are starting to feed, at least south of Interstate 70, and will probably be hatching and feeding north of I-70 shortly after the return of warm weather."

Information about treatment thresholds and insecticide recommendations is available at county and district K-State Research and Extension offices.

SOURCE: K-State Research and Extension news release.