Abstract
Folic acid antagonists inhibited oviposition by screw-worm flies [Cochliomyia hominivorax (Coquerel); Diptera: Calliphoridae]. Fertility was unaltered when sufficient folic acid was administered simultaneously, or it was partly restored spontaneously about 2 weeks after treatment. Folic acid antagonists principally affected only maturing eggs at any age, rather than those already matured.