Diamondback moths may be a mere half-inch in length, but their voracious appetite for Brussels sprouts, kale and cauliflower make them a major pain for farmers. This week, the US Department of Agriculture approved a potential solution: Moths genetically engineered to contain a special gene that makes them gradually die off. A field trial slated to take place in a small area of upstate New York will become the first wild release of an insect modified using genetic engineering in the US.