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Headclipper Weevil

The adult sunflower Headclipping weevil (Haplorhynchites aeneus Boheman) is shiny black and about 5/16 inch long. Larvae are cream colored and C-shaped and grub-like in appearance.

Life Cycle: Adults emerge in mid-July and may be found on plants for 2 to 3 weeks. Females feed on pollen and nectar of flowering heads. Eggs are laid in the head. The female feeds around the neck of the stalk causing the head to break off. The larvae develop and overwinter in the fallen head.

Damage: Damage is usually sporadic and localized on field margins and the insect is most often found in the High Plains. There have been reports of 20% clipped heads in some fields. Economic Thresholds: This is not well defined. Insecticide application may be advisable if one out of every two plants has an adult present and if head clipping exceeds 5% on average across the field. Scouting Method: The familiar X pattern is recommended for counting adults. Management: Insecticide application may be advisable if one out of every two plants has an adult present and if head clipping exceeds 5% on average across the field. Research: Work on this insect has been very limited due to its lack of economic injury. Photos: Visit the Photo Gallery. Source: High Plains Sunflower Production Handbook, June 2005

High Plains Sunflower Production Handbook  file size: 1554 kb