The cotton bollworms, Helicoverpa armigera (old world bollworm) and Pectinophora gossypiella (pink bollworm), are insect pests of cotton. Adult cotton bollworms are moths. The adult female moths lay eggs on cotton plants. The eggs hatch into larvae. The larvae feed on cotton plants, causing extensive damage and reduction in yield. Fig. 2.1 shows a mature cotton fruit (cotton boll) from an uninfested plant. Fig. 2.2 shows a cotton bollworm inside a developing cotton boll. [Figure 2.1] [Figure 2.2] A gene, cry1Ac, from the bacterium Bacillus thuringiensis (Bt), can be inserted into the cotton genome to produce 1 cry gene Bt cotton. • 1 cry gene Bt cotton produces the protein Cry1Ac, which is toxic to some species of bollworm. This toxicity gives cotton plants some resistance to cotton bollworm. An additional gene, cry2Ab, can be inserted into the cotton genome with cry1Ac. This produces 2 cry gene Bt cotton. • 2 cry gene Bt cotton produces two different proteins, both toxic to cotton bollworm.