(A) Female natural mating behavior: the female follows the tail-waving male, touches the male's tail to stimulate spermatophore deposition, and uses tail-waving to encourage a male to continue courtship (see Materials and methods). (B) Equivalent female behavior in a two-female experiment: after addition of male courtship water, one female follows the other one, or both females try to follow each other; the following female regularly touches the tail of the other one; a female uses tail-waving in trying to encourage the other female.