Bt-cotton plant is a transgenic plant which produces an insecticide to bollworm. Bt-cotton is produced by inserting cry gene from bacteria Bacillus thuringiensis to the plant genome by the help of transgenic technology. The genetically modified DNA in recipient plant produces toxin in sap. When the insect attacks on the plant and suck the sap from the plant, these toxin binds with the gut wall of the insect. These proteins create pores in the gut. This results in damage to the cells and blocks the gut which leads to the death of the insect.