Soak the leaves overnight or pound the leaves with a heavy stick like a baseball bat and soak overnight. If not pounded, remove the leaves to another bowl or bucket . And keep the water. Pound the leaves. and squeeze out the liquid. NSKE is effective for a variety of leaf eating insects. Aphid, shoot and fruit borer, pod fly etc. NSKE (5%) and neem oil (0.5%) were very effective in controling cotton white fly. And many farmers use this process.