The impact of prior captures on the trapping performance of floor traps was evaluated for the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), and the confused flour beetle, Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae), in laboratory conditions. The effect of trap seeding, adding adults of the same or different species, was evaluated in order to determine possible effects of prior captures in the trap on each species' behavioral responses. The presence of seeded beetles of the same species resulted in an increase in beetle captures for both T. castaneum and T. confusum, but when traps were seeded with the opposite species, there was no increase in beetle captures for either species, and for T. castaneum overall captures in both seeded and unseeded traps was reduced. Overall, T. castaneum tended to have greater captures than T. confusum regardless of the treatment. When the two species were released together, this negated the increased response to seeded traps observed in the single-species treatments. These findings suggest the potential that the presence of beetles in a trap may be influencing the response of beetles in a nearby trap and that T. castaneum and T. confusum when they occur together may influence each other's response to traps.