HPIPM:Sunflower Receptacle Maggot

Author: Frank B. Peairs[1]

Field Biology and Identification

The sunflower receptacle maggot adult, Gymnocarena diffusa (Snow), is a small fly about 10 millimeters (5/16 inch) long, with a wingspan of about 18 millimeters (3/4 inch). The eyes are bright green and wings have a brown mottled pattern. Larvae are yellowish white in color and tapered from front to rear. Mature larvae are about eight millimeters (5/16) in length. Adults emerge in June to early July and lay eggs on bracts of developing sunflower heads. After about 30 days, the mature larvae drop to the soil to pupate in late August or early September. Overwintering pupae are found over six inches under the surface. Some larvae will pupate in the sunflower head. There is one generation per year in this region.

Plant Response and Damage

Mature larvae cut a small emergence hole on the underside of the receptacle. Significant yield losses have not been demonstrated with this insect.

Management Approaches

Chemical Control

Insecticide treatments generally are not considered necessary.

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.