Sunflower XIV-7

Head-Clipper Weevil

Frank B. Peairs

Weevil adult, left; Larva, right.

Field Biology and Identification

The adult head‑clipper weevil is shiny black, measuring about eight millimeters (5|16 in.) from the tip of the snout to the rear of the abdomen.  Larvae are cream colored, C-shaped and grub‑like in appearance.  Adults emerge in mid July and may be found on plants for a two to three week period.  The females feed on pollen and nectar of flowering heads.  After making a series of punctures around the circumference of the stalk just below the head, the female lays an egg in the head.  The girdled head falls to the ground where the larvae develop and overwinter inside the fallen head.

Plant Response and Damage

The percent of "clipped heads" is usually very low but may reach 20 percent in some fields.  Damage is often limited to field margins.

Management Approaches

Chemical Control

When scouting, sample sites should be 75 to 100 feet from the edge of the field.  Use an "X" pattern, counting weevils on five heads per sampling site for a total of 25 heads.  A threshold level has not been determined.

Categories: Sunflower, Insects, Head clipper weevil

Date: 04/16/2004