Information for this article was compiled by Dr. Kevin Wanner (MSU Extension Entomologist) and Dr. Emily Glunk (Previous MSU Extension Forage Specialist).
Alfalfa weevil is the key insect pest of alfalfa, causing variable levels of economic
damage across Montana. Females lay eggs in alfalfa stems. Larvae hatch and crawl up to developing terminal buds where they chew small “pin” holes in the leaves. Larvae develop through four instar stages. Larger 3rd and 4th instar larvae feed openly on unfurled leaves and cause the largest economic loss. Severe feeding damage will give the field a “frosted”...
