NOVELTY - Bollgard (RTM: Insect-resistant cotton) leaves phosphate extract comprises Bollgard (RTM: Insect-resistant cotton) leaves, dipotassium phosphate, monopotassium phosphate and water.    USE - The extract is useful for preventing and killing Hyphantria cunea and other insects.    ADVANTAGE - The extract: is ecofriendly and economical in comparison with the conventional extracts; does not cause drug resistance in comparison with cypermethrin; and solves the problem of slow reproduction and high cost in prevention and treatment by natural means.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing the Bollgard (RTM: Insect-resistant cotton) leaves phosphate extract, comprising: (i) selecting Bollgard (RTM: Insect-resistant cotton) leaves, which is an optimized Bollgard (RTM: Insect-resistant cotton) leaves approved by the provincial level and containing Bacillus thuringiensis (Bt) insecticidal protein, capable of continuously producing Bt insecticidal protein or cotton bollworms; (ii) selecting cotton leaves preferably 3-4 layers downwards from the top of the cotton plant and washing; (iii) weighing dipotassium hydrogen phosphate, adding into water to prepare a solution, and weighing potassium dihydrogen phosphate, adding with water to prepare monopotassium phosphate solution (1 mol/l), where the volume ratio of dipotassium phosphate solution to monopotassium phosphate solution is 187.2:12.8, mixing the two solutions and making the volume up to 1000 ml to prepare a phosphate buffer solution (0.2 mol/l) of pH 7.9-8.1; and (iv) weighing the phosphate buffer solution and Bollgard (RTM: Insect-resistant cotton) leaf in a weight percentage of 100:0.2 mol/l, crushing the Bollgard (RTM: Insect-resistant cotton) leaves into 200-800 mm2, adding into a juicer, mixing and stirring with the phosphate buffer solution, pouring into a vessel, oscillating in an ultrasonic oscillator for 9-11 minutes, allowing to stay at 1-5 degrees C for 20-26 hours, filtering through 50-100 meshes filter, and preparing into 1:(9-12) % of Bollgard (RTM: Insect-resistant cotton) leaves phosphate extract and using the Bollgard (RTM: Insect-resistant cotton) leaves phosphate extract as a mother liquor.