An investigation was carried during the winter seasons of 1999-2001 to study the larval incidence and damage relationship of Helicoverpa armigera Hubner in cotton (Gossypium hirsutum L.) at Coimbatore. There was a strong and positive correlation (r = 0.74, 0.71, 0.75 and 0.63) between larval number and damaged fruiting bodies. It also revealed that 43-57% of sampled plants were infested with single larva and 30-37% with 2 larvae and 18-21% with 3 to 4 larvae during the peak infestation periods, viz 77-100 days after sowing. The fruiting bodies damage was 10.13, 20.44, 30.25 and 38.61% for 1, 2, 3 and 4 larvae/plant respectively. The larval population which caused 5% fruiting bodies damage was 0.5 larva/plant.
