Larvae do the most damage, although adult alfalfa weevils are also injurious. Early season feeding in leaf buds and terminal growing areas may seriously retard normal plant growth. As the larvae grow, they feed on leaves, and eventually skeletonize them. The larvae can easily be seen curled around stems or leaves. As feeding persists, an infested field takes on a distinct grayish appearance.
Adult weevils notch main stems, side shoots, and leaf stems.
They often sever the latter two from the plant. They also feed on the leaves, causing ragged and torn leaf margins. Females puncture the stem during oviposition. Feeding damage by both adults and larvae greatly reduces the quality and yield of the first cutting of hay, and may reduce the quality of subsequent cuttings. Adult weevils, 4.0 to 6.5 mm long, oblong, convex, brown to blackish, with 3 clear bands formed of bifid hairs.