Eight potential oviposition attractants were evaluated for gravid Culex tarsalis and Cx. quinquefasciatus under insectary, outdoor cage and field conditions. With the possible exception of a steer manure infusion under insectary conditions, none of the media consistently attracted large numbers of gravid Cx. tarsalis females. Reiter medium, steer manure infusion, cattle feces and Bermuda sod were attractive to gravid Cx. quinquefasciatus. Catch size at CDC gravid traps and oviposition traps were sensitive to the number of competitive oviposition sites and trap placement.