FemaleEucosma womonanaKearfott had a preoviposition period of 4.4 ± 0.5 days, after which they laid an average of 236.8 ± 18.1 eggs in the laboratory at 27 ± 2°C. Incubation averaged 6.3 ± 1.5 days. Larvae passed through five stadia in ca. 85.8 ± 6.8 (females) or 86.5 ± 6.9 days (males). The total life cycle for laboratory-reared specimens averaged 106.7 ± 4.7 days. Infestation of roots of sunflowers,Helianthus annuusL., byE. womonanalarvae on the High Plains of Texas was significantly reduced in plantings made after late April in 1982 and mid-May in 1983.