Five male entocytherid ostracods of four different species recovered from signal crayfish Pacifastacus leniusculus were observed exhibiting false mating behaviors with either another adult male, an A1 sub-adult male, or an A3 juvenile of indeterminate species and sex. In all five instances, the ostracod being mated was not sclerotized, indicating recent molt. In one case, a male of Uncinocythere thektura was observed in false copulation with an A1 male of a different species, U. occidentalis, suggesting that taxonomic designations of females in mixed populations of Uncinocythere can be problematic. Possible reasons for false mating behavior include stress of being confined post-collection, lack of available females, or possibly males mistaking non-sclerotized partners for A1 females.