Two years of intense sampling showed that boll weevil, Anthonomus grandis Boheman, adults initially move into cotton in the Lower Rio Grande Valley of Texas prior to squaring. Punctured squares were infestation level of 2.3 and 0.3% punctured squared in untreated study areas resulted in virtually (> 90%) all of the fruiting body infested after 75-85 days. Boll weevils appeared to move into fields at random with infestations becoming aggregated in sites over the entire field prior to maturity of 1st generation weevils, punctured fruiting bodies increased in number and the infestation appeared random to slightly aggregated in nature in untreated plots. In areas where insecticides were applied the infestation remained highly aggregated for much longer periods after emergence of 1st generation individuals.