If environmental conditions are favorable, larvae may survive both cutting and harvest and feed on newly forming crown buds, which significantly delays regrowth and lower yields.
Check to make sure crown buds are forming.
Look for larvae on the soil surface, under leaf litter and at the juncture between soil and the alfalfa crown. During cool, cloudy weather you may find weevils feeding on new alfalfa buds during daylight hours. You may also see increased survival under windrows.
It is difficult to make control decisions based on the number of larvae found. A better method is to take another stem sample, as you did with first crop, and treat the field when 50 percent of the stems have feeding injury.
Before deciding to spray, use an insect sweep net to make sure weevils are still present and check for presence of pupae -- a sign that feeding may be slowing down. FG
—From Wisconsin Crop Manager
