Effects of damage caused by the American bollworm,Heliothis armigera(Hbn.), on yield of tomato,Lycopersicum esculentumMill., transplanted at different times were studied in 1985–6 by treatment with some insecticides against this insect. Fruit damage was highly but negatively correlated(P =001) with the number (r= ‐0.69, 1985; ‐0.98, 1986); weight (r = ‐0.78, 1985; ‐0.64, 1986); and yield(r= ‐0.74, 1985; ‐0.90, 1986) of harvested fruits. Fruit damage was significantly reduced and yield increased by spraying thus showing serious damage was caused byHeliothis.Cypermethrin suppressed fruit damage by 70.4 and 52.2% in 1985 and 1986 and increased yield by 1150 and 67.6%, respectively.