Insecticides have been used for centuries to counteract widespread pest damage to valuable food crops. Eventually, over time, beetles, moths, flies and other insects develop genetic mutations that render the insecticide chemicals ineffective. Insecticides have been used for centuries to counteract widespread pest damage to valuable food crops. Eventually, over time, beetles, moths, flies and other insects develop genetic mutations that render the insecticide chemicals ineffective. Molecular & Computational biology Agriculture Phys.org – latest science and technology news stories