A new class of insecticides, based on synthetic nicotine and known as neonicotinoids, were introduced in the 1990s. Because they kill insects but are nontoxic for humans and mammals, they won rapid approval by regulators and wide adoption by farmers. But they have become the focus of intense controversy over their effect on bees since colony collapse disorder was first identified in 2006. Hover over map for county data.
Imidacloprid use in pounds by county
Sources: USDA; National Agricultural Statistics Service (NASS), USGS National Water-Quality Assessment (NAWQA) Program, U. of M. Dept. of Entomology, NIFA, Star Tribune reporting