The method described in this paper uses wheat, Triticum aestivum L., grown in a greenhouse as the rearing medium for thrips forced to move to cotton, Gossypium hirsutum L., seedlings after the wheat was killed with herbicide. As measured by numbers of thrips and reduction of leaf surface area, the method produced abundant thrips pressure and was useful for initial evaluation of cotton for resistance. The method was used to evaluate cotton seedlings for six years and had a 0% failure rate. Western flower thrips, Frankliniella occidentalis Pergande, followed by onion thrips, Thrips tabaci Lindeman, were dominant during the study. Numbers of thrips of other species were scarce.