University of Illinois Extension

University of Illinois Extension

Hort Answers

Insect Damage

Imported Crucifer Weevil
Baris lepidii Germar




Imported crucifer weevil adults are metallic blue-black and only about 1/10 inch long. Their mouthparts are at the end of an obvious, elongate "snout" that protrudes forward and down from the head. The adults use this snout to chew egg-laying holes in the roots. The resulting larvae are stout, legless, white larvae that tunnel along the root surface. The larvae pupate in these tunnels and emerge as adults. There are two generations per year.

Larval tunneling can be extensive enough to reduce yield or even kill sets. These surface tunnels reduce the market value of the roots.

Life Cycle

Imported crucifer weevils have been in Illinois and the mid-west for more than 35 years. The adults overwinter in unharvested roots and sets that are in cold storage. Since the adults cannot fly (most weevils have fused wings that make them flightless), they walk to the new plants to feed or are carried through human movement of plant material.. Eggs are laid in the spring. Legless larvae emerge and feed on plant roots. These weevils pupate in the roots before emerging as adults. There are two generations per year in the mid-west.

Crop rotation, along with the control of volunteer horseradish, is effective. Although imported crucifer weevil has fully developed wings, it primarily walks to new hosts or is carried through human movement of plant material. At planting, treat sets with an insecticide if they are infested or the fields have a history of weevil damage. Examine crowns in early August and apply foliar sprays if adult weevil populations exceed one to three per ten plants, or use the field's weevil history to determine the potential for damage.

Related Resources
Home, Yard & Garden Pest Guide
Illinois Commercial Landscape and Turfgrass Pest Management Handbook
U of IL - Distance Diagnosis through Digital Imaging
U of IL - Plant Clinic