Reciprocal double mating experiments were done between the northern banded (disruptively colored) form [Limenitis arthemis arthemis (Drury)] and the southern unbanded mimetic form [L. arthemis astyanax (F.)] of the banded purple butterfly. The results showed that following a second mating (and the successful transfer of a second spermatophore into the bursa copulatrix of each female), the first male continued to sire the subsequent progeny in five of 17 (29%) cases. The sequential double matings of these 17 different females with 34 different males resulted in full, partial, and unbanded wing phenotypes which were used as paternal genetic markers in this intergrading complex of butterflies. The containment of the spermatozoa within separate spermatophores at the time of mating normally resulted in only one effective sire. Among three broods (all one of four cross types) some sperm mixing may have occurred following the second matings, as evidenced by the occurrence of a few unbanded insects among progeny which otherwise were partially banded. The evolutionary implications of these findings are considered as they relate to insect mate-seeking strategies and individual fitnesses.