Bollworm is the common term for a moth larva that attacks the fruiting bodies of certain crops, especially cotton. The most common moths known as bollworms are:
Red or Sudan bollworm, Diaparopsis
Rough bollworm, Earias perhuegeli
Spotted bollworm, Earias fabia
Spiny bollworm, Earias insulana
Spotted bollworm, Earias vittella
American cotton bollworm or tomato grub, Helicoverpa armigera
Cotton bollworm, Helicoverpa gelotopoeon
Cotton bollworm, Helicoverpa punctigera
Corn earworm, Helicoverpa zea
Tobacco budworm, Heliothis virescens
Pink bollworm, Pectinophora gossypiella
Pink spotted bollworm, Pectinophora scutigera
They eat all sorts of things eg: cotton plants. They cost cotton growers a lot of money throughout the growing season, having to spray the bollworms can cost over $5000, about three times a year.
