RESUMO
The objective of this research was to evaluate the incidence of damage by the leafworm Alabama argillacea (Hübner) on yields of cotton grown under rows spaced 0.38 m and 0.76 m at the irrigation area of Santiago del Estero, Argentina. The period evaluated was extended from first flower to first open boll. Treatments were T1 - without control of larvae, T2 - with control of larvae, T3 - control since first flower to the end of effective blooming, and T4 - with larval control since the end of effective blooming to first open boll. The effect of injuries on the crop was evaluated trough boll cotton yield. Larvae were sampled in a weekly basis and insects were present from the first flower until harvest. Populations of A. argillacea decreased crop yields in the two distances tested, by decreasing the weight or number of open bolls.