none Research was conducted in the Lower Rio Grande Valley of Texas to evaluate the technical feasibility of natural enemy augmentation as a means of suppressing infestations of boll weevil,Anthonomus grandis Boheman, in stands of undestroyed cotton during the postharvest fallow season. Augmentative releases of Catolaccus grandis (Burks) and Bracon mellitor (Say) at relatively high rates within a 0.1-ha experimental plot ( apprx 4,000 and apprx 2,000 mated female parasites/ha/wk, respectively, during 22 Sept - 6 Oct 1993) was accompanied by a significant increase in densities of the former and a slight increase in the latter (to peaks of 14.0 and 0.4 immature parasites/m-2 by 6 October). Parasitism by C. grandis was largely concentrated among third-stage weevil larvae infesting abcised cotton squares, but caused appreciable mortality within this segment of the host infestation (90.6% apparent). The relatively high incidence of host mortality caused by parasitism within this infestation served to destroy significant numbers of immature boll weevils that appear to have been predisposed to successfully overwinter.