Clover Leaf Weevil in Alfalfa
Published: 03/23/2022
Crop Injury: Clover leaf weevil (Hypera zoilus) has been present in the U.S. for more than 140 years. Adults and larvae consume alfalfa foliage starting in the lower plant canopy and moving upwards. Leaves with feeding injury appear ragged and severe plant defoliation can occur with high weevil populations. Clover leaf weevil prefers to feed during the night or under cloud cover, retreating to the alfalfa plant base when it is sunny.
Pest Description: Adult weevils are dark brown and speckled with lighter- and darker-colored scales. Adults have a faint stripe on each wing cover and are 5/8 inch in length. Legless larvae have a brown head, are yellow to green with a single white stripe with pinkish borders along the back.
Clover leaf weevil
Whitney Cranshaw, Colorado State University, Bugwood.org
Clover leaf weevil
Whitney Cranshaw, Colorado State University, Bugwood.org
Life Cycle: Overwintering occurs most commonly as larvae or eggs. Larvae become active in late winter to late spring and feed on plants. Cocoons are formed on or near plants, protecting the insect during pupation. Emerging adults consume alfalfa tissue and then become inactive until fall egg laying. Clover leaf weevils have one generation per year.
Scouting: Clover leaf weevil can be confused with alfalfa weevil. Check fields right after the first cutting, especially when weather conditions have been dry.
Management: A fungal pathogen which thrives in warm and wet conditions typically keeps clover leaf weevil populations low. Be aware that weevils may flourish during cool and dry springs, when fungal development is limited. Insecticide application can control clover leaf weevils.
Prepared and reviewed by the Alfalfa Pest Management Working Group.
Clover leaf weevil. Whitney Cranshaw, Colorado State University, Bugwood.org
Clover leaf weevil. Whitney Cranshaw, Colorado State University, Bugwood.org
Gallery images courtesy Whitney Cranshaw, Colorado State University, Bugwood.org.
This publication was developed by the Crop Protection Network, a multi-state and international collaboration of university/provincial extension specialists and public/ private professionals that provides unbiased, research-based information to farmers and agricultural personnel.
This information in this publication is only a guide, and the authors assume no liability for practices implemented based on this information. Reference to products in this publication is not intended to be an endorsement to the exclusion of others that may be similar. Individuals using such products assume responsibility for their use in accordance with current directions of the manufacturer.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD).
USDA is an equal opportunity provider and employer.
©2022 by the Crop Protection Network. All rights reserved.
