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Midge
The adult sunflower midge (Contarinia schulzi Gagne') is about 0.07 inch long with a wingspan of about 0.19 inch. The wings are transparent with no markings. The adult is tan in color. The larva is tiny as well, about 1/8 inch long when fully grown and cream to yellowish orange.
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Midge larva in sunflower head
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Life Cycle: Adults overwinter in the soil and emerge in June and July in the ND, MN and Manitoba. The adult lives for only a few days and are difficult to find in the field. The adults lay eggs in the bracts and the larvae feed on the edges of the head and migrate into the center of the head as the head develops. The larvae mature and drop to the soil and over winter. A second generation occurs in August.
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Damage: Damage is usually sporadic and localized on field margins. When infestations are severe, the bud may not fully develop or the head becomes gnarled and twisted resulting in significant yield reduction.
Economic Thresholds: None has been established.
Scouting Method: None has been established.
Management: Chemical controls are not available. Rotation and varied planting dates are good management tools. Some hybrids are more tolerant to midge damage. USDA and NDSU have conducted hybrid resistant trials for many years. Producers seeing increasing damage in field margins should consider planting the most tolerant hybrids available the following year.
Research: Hybrid seed companies and the USDA ARS located in the Red River Valley of the North have been selecting resistant parent lines for over 25 years through natural infestation. This has resulted in better hybrid tolerance. The NSA has supported annual hybrid testing/rating at a location that has had consistent midge pressure over many years.
Photos: Visit the Photo Gallery.
Source: NDSU Extension Bulletin 25 Sunflower Production Handbook, NDSU Extension Service, September 2007. The Sunflower Production Guide, Manitoba.
For further information, click on the links below. Another resource about Insects can be found in the Archive section of The Sunflower magazine.
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Additional Documents
NDSU Extension Bulletin 25 - Revised 9/2007 (document) File Size: 5461 kb
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