Transfers of sediments from old farm ponds to newly constructed mesocosm test ponds in autumn facilitate rapid establishment of taxonomically rich communities of benthic organisms for use in studies of pesticide effects the following summer. It has been presumed, but not critically demonstrated, that the sediment transfers conserve patterns of benthic organization and thus provide a test fauna highly representative of the undisturbed source ponds. Comparisons of emergence composition and phenologies of Chironomidae (the dominant taxon in our mesocosm tests) from mesocosm ponds at the Nelson Environmental Studies Area with historical patterns of Chironomidae emergence in Kansas confirm high degrees of representativeness among Chironomidae emerging from mesocosm ponds. Species richness of Chironomidae emerging from mesocosm ponds within one year after seeding with transferred sediments is higher than recorded for ponds where aerial colonization by ovipositing females is the primary source of Chironomidae. Species richness, emergence composition, chronology, and phenology compare favorably with results of studies of Chironomidae emergence dynamics from small ponds with mature sediments.