If hermaphrodite C. elegans can reproduce with females?
Since only the male tail is equipped with various specialized sensory and copulatory structures that enable him to locate the vulva and successfully inseminate the hermaphrodite.  Hermaphrodites can self-fertilize, but only males can cross-fertilize a hermaphrodite.

sources: Wormbook: Male development
C. elegans II (2nd edition): Sexual Dimorphism