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How to identify it
- Larvae are legless, yellow to green, with a brown head and a white stripe down the back. In older larvae the stripe often has pinkish edges. Full-grown larvae are just under 1/2 inch long.[1][2]
- Adults are brown weevils speckled with lighter and darker scales, with a faint stripe on each wing cover. They look like alfalfa weevils but are much larger.[1][2]
- Scientific names vary by source: iNaturalist uses Brachypera zoilus, Kansas State uses Donus zoilus and the Crop Protection Network Hypera zoilus, and older literature also calls it Hypera punctata.[1][2][3]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Alfalfa weevil | Alfalfa weevil larvae are also green with a white line down the back, but they have a black head and feed on the upper growing tips. Clover leaf weevil larvae have a brown head, feed on the lower parts of the plant, and are noticeably larger when full grown.[1][2] |
Where it lives
A native of Europe, it has been in the United States for more than 140 years and is now established in most areas of North America where clover and alfalfa are grown.[1][2]
Biology and life cycle
There is one generation a year. Adults lay yellow, oval eggs around their host plants, usually in the fall. Most eggs hatch in fall, though some wait through the winter, and a few adults may survive the winter and lay eggs on mild days.[1][2]
Young larvae feed during mild spells through the winter and become active from late winter into spring, reaching full size between late March and early May.[1][2]
Larvae feed mostly at night or under cloud cover and spend sunny days hiding in leaf litter around the crown.[1][2]
Full-grown larvae pupate in an oval cocoon just under the soil surface or in debris near the base of the plant. The new adults feed for a few days, then stay inactive through most of the summer until fall egg laying.[1][2]
Damage and signs
Health risk
Kansas State and the Crop Protection Network describe it only as a pest of alfalfa and clover and mention no risk to people or animals.[1][2]
Control
Prevention
Scout by examining the crowns of 20 plants in five different parts of the field, since larvae hide there by day. Check fields right after the first cutting, especially in dry weather.[1][2]
Biological control
Disease and parasites normally keep it under control. A fungal pathogen that thrives in warm, wet weather usually holds populations low, so weevils can build up in cool, dry springs when the fungus does poorly.[1][2]
Pesticides
Kansas State considers insecticides justified only when crowns average five or more healthy larvae. The Crop Protection Network notes that insecticides can control it.[1][2]
Common questions
- How do I tell clover leaf weevil larvae from alfalfa weevil larvae?
- Look at the head and where they feed. Clover leaf weevil larvae have a brown head, feed low on the plant at night and hide at the crown by day; alfalfa weevil larvae have a black head and feed in the growing tips. Full-grown clover leaf weevil larvae are also noticeably larger.[1][2]
- Do I need to spray for clover leaf weevil?
- Rarely. A fungal disease and parasites usually keep it in check. Kansas State sets the threshold at an average of five or more healthy larvae per crown.[1][2]
- Why are clover leaf weevils worse some years?
- The fungus that usually suppresses them thrives in warm, wet weather. In cool, dry springs the fungus develops poorly and the weevils can flourish.[2]
Sources
- Kansas State University Department of Entomology, “Clover Leaf Weevil (Alfalfa Pests).” entomology.k-state.edu/extension/crop-protection/alfalfa/clover-leaf-weevil.html (accessed 2026-11-08)
- Crop Protection Network, “Clover Leaf Weevil in Alfalfa (Alfalfa Pest Management Working Group, 2022).” cropprotectionnetwork.org/encyclopedia/clover-leaf-weevil-in-alfalfa (accessed 2026-11-08)
- iNaturalist, “Brachypera zoilus taxon page (order and family).” www.inaturalist.org/taxa/455794 (accessed 2026-11-08)