Insects including corn rootworm and bollworm have also begun showing signs of resistance. The cotton bollworm is a highly polyphagous species. Helicoverpa gelotopoeon, the South American bollworm moth, is a moth of the family Noctuidae. Earias biplaga, the spiny bollworm, is a moth in the family Nolidae. The bollworm threatens cotton, soybean, corn, and tomato crops. The flax bollworm ("Heliothis ononis") is a species of moth of the family Noctuidae. However, recently cotton bollworm has been developing resistance to Bt cotton. They concluded that the GM cotton effectively controlled bollworm. Bergtheil's cotton scheme failed after the first two crops were ravaged by bollworm. They attempted to grow cotton but had problems with bollworm. The cotton bollworm is very variable in both size and colour. His early work was in examining the natural parasites of bollworm in Surat.