White fly harm the cotton crop adversely. Due to this the leaves curls down. It generally attacks the crops during rainy season or during the days when humidity is high.
For its prevention make a solution of 100 grams camphor(Mushak kapoor) in mild warm water and then mix it in 100 litre of water and spray it in an acre. Other than this you can also prevent it by making the solution of 100 grams of Asafetida (Hing) in warm water and after that mix it with 100-130 litre of water and spray it in acre. By following these steps you can prevent the attack of white flies.