The Boll Weevil, Anthonomus grandis Boheman, is the most important insect pest to cotton production in Mexico, particularly in the Northeast. The present experiment was conducted in the Southern Region of Tamaulipas, Mexico, near the Tropic of Cancer, in the Summer of 1996. Two cotton fields of four hectares each were used. In one of the fields only females of Catolaccus grandis (Burks) were released to control early infestation of boll weevil, A. grandis Boheman. In the other field boll weevil infestations were controlled according to commercial insect management; that is, insecticide spray when economic threshold was reached. A total of 14 releases were made twice a week except the last one which was made seven days apart. An average of 950 adult females per hectare were released (380 adults per acre). For cohort life table analysis, infested squares (eggs or first instar larva) from commercial cotton check field were collected and grouped ten per cord. The number of groups varied according to the availability of infested squares ( 6 to 12 every date). These were left on the field for two weeks, then they were picked up and taken to the laboratory for analysis. For interpretation purposes, the results of cohorts were grouped in three seasons (early, mid and late seasons). Results obtained showed that Catolaccus grandis is the main mortality factor for third instar boll weevil larvae in both aspects known; that is, as parasitoid and adult feeding habits in second and third instar larvae. The highest mortality was obtained during the early season followed by the mid season. The results obtained in the check field showed that parasitoids did not represent an important mortality factor for boll weevil. A total of 10 sprays were applied in the commercial field, 7 for boll weevil control and 3 for other insects such as aphids and bollworm. In the release field, only 3 sprays for boll weevil were needed. Yield of seed cotton was similar in both fields.