On April 15, Tom Hillyer from West Liberty in Muscatine County found alfalfa weevils actively feeding. Timely scouting . Large populations of alfalfa weevil can be very destructive to the first-cutting of alfalfa. Forage yield and quality is reduced by the loss of leaf tissue from feeding activity, starting at stem tips and progressing down the stem. Larvae are small and not readily noticed during early stages.
Large populations can cause significant damage before damage becomes obvious to the casual observer.
The map on page 62 shows accumulated degree days for the nine crop reporting districts in Iowa, and a projected date to begin scouting is provided for each district. South-facing slopes tend to warm up faster and are typically the first areas to check for alfalfa weevil larvae. Correct Identification . Alfalfa weevil larvae are pale green with a white stripe down their back. Their heads are black.