The dispersion of the cotton boll weevil, Anthonomus grandis , within a field after the hibernating weevils have become established is periodic. Each period of dispersion coincides with the emergence of a new brood of weevils. The spread of weevils across a field is usually direct from plant to plant or row to row and is not the result of long flights. Newly emerged weevils do not usually migrate until sexual maturity is attained. This information has been used in locating infestations at the beginning of the second and third periods of dispersion and in timing dust applications. Small infested areas dusted before weevils reached sexual maturity resulted in apparent extermination of infestation.