Nebraska alfalfa growers should begin monitoring for alfalfa weevil feeding this week, according to University of Nebraska entomologists. Most weevils overwinter as adults, become active and lay eggs. But some eggs overwinter and hatch early, which is what happened in areas such as the panhandle and northern tier of counties. They were hit with two flushes of weevils this spring. In some areas the last few years, regrowth after first cutting was damaged by a combination of late larval feeding and adult feeding. Producers need to be alert to this potential problem.
Clover leaf weevils, a problem only when spring rains are rare, built up populations in western Nebraska. But recent rain could have lowered those numbers. Larvae will be in debris around the crowns during the day. Scratch in the soil around the crowns and count the number of larvae found per crown. Their brown heads help distinguish them from the black-headed alfalfa weevil.
Alfalfa and clover leaf weevils feed on first-cutting alfalfa as larvae, and first-cutting regrowth as larvae and adults. Northeastern Nebraska research has shown that clover leaf weevil larva feedings don't reduce alfalfa yields in first cuttings, but alfalfa weevil feeding can cause severe yield and quality losses.
Source: University of Nebraska.