Beet armyworm (Lepidoptera: Noctuidae) behavior and effects on insecticide efficacy in open and closed cotton flowers and boil abscission or damage from flower infestation

Severe natural infestations of the beet armyworm, Spodoptera exigua (Hubner), in upland cotton, Gossypium hirsutum L., result in newer infestations as well as foliage infestations. Conventional insecticide applications did not control beet armyworms in the flowers when applications were applied in early morning before the flowers opened. This problem was remedied by delaying applications until flowers opened before initiating insecticidal control. Two tests were conducted to determine the validity of the observation. In both tests, insecticidal control was greater than or equal to 96% when flowers were open and less than or equal to 12% control when Bowers were closed. In a 3rd test, flowers were infested with beet armyworm larvae to determine if that would inhibit bell development or increase boil abscission. Seven days after the infestation, there was a significant reduction in bells developed from infested flowers compared with that in bells from noninfested flowers.