The eggs normally are laid singly on terminal buds, terminal leaves, or blooms and squares. At certain times, moths seem to prefer the lower portions of a plant for egg laying. Newly hatched bollworms can be found feeding on terminals and very small squares. As bollworms increase in size, they tend to feed downward, attacking larger squares, blooms, small bolls, and finally nearly full-grown bolls. While natural outbreaks sometimes occur, severe outbreaks usually follow insecticide applications meant to control other pests.
Bollworms occasionally are present early in the season before any bolls have formed.
In cases where no insecticides have been applied to a field, natural control usually is excellent and little damage results. However, if bollworms are damaging more than 5 percent of the squares, insecticide treatment may be justified. The greatest danger of bollworm outbreak is in midseason after most corn has stopped silking. Bollworm moths are attracted to cotton in bloom. From this time until the end of the fruiting season, check fields weekly for bollworms.