How an insect pest switches from sluggish super breeder to flying invasion machine. Duke Today, March 18, 2015. Each year, the rice crop in Asia faces a big threat from a sesame seed-sized insect called the brown planthopper. Now, a study in the journal Nature reveals the molecular switch that enables some planthoppers to develop short wings and others long based on environmental conditions such as day length and temperature — a major factor in their ability to invade new rice fields.