An investigation was conducted concerning the effect of mirex bait on production and survival of red crawfish, Procambarus clarki (Girard), in rice fields of southern Louisiana. Twenty experimental plots were stocked with 2,000 brood crawfish (50 pairs per plot). Each plot was randomly assigned to one of four treatments: (1) conventional rice insecticides, malathion and carbofuran; (2) mirex alone; (3) mirex in conjunction with malathion and carbofuran, and; (4) untreated controls. Mirex bait (0.3 per cent technical material) was applied at the rate of 1.25 pounds per acre in three applications, approximately 90 days apart. Statistical analyses of data revealed no significant differences among treatments in crawfish size, sex ratio, and weight yield, whereas the differences among treatments in number harvested were significant (P .05). Plots treated with mirex alone produced the fewest crawfish (3,642) and control plots the most (5,667). The treatment consisting of mirex, malathion, and carbofuran, however, produced the second highest number (5,637); slightly below the total collected from control plots. Orthogonal comparisons indicated that the disparity among treatments was not due to mirex activity. Mirex residues in crawfish from plots receiving mirex applications averaged 0.248 ppm (range 0.092.01 ppm) on a whole-body basis, which is above the tolerance established for mirex in fat of red meat (0.1 ppm).
