Clothianidin is the pesticide at the center of controversy. It is used to coat corn, sugar beet and sorghum seeds and is part of a class of pesticides called neonicotinoids. The pesticide was blamed for bee deaths in France and Germany, which also is dealing with a colony collapse. Those two countries have suspended its use until further study. An EPA fact sheet from 2003 says clothianidin has the potential for toxic chronic exposure to honey bees, as well as other pollinators, through residues in nectar and pollen.
Lawsuit seeks EPA pesticide data
Interesting story. For more on the Colony Collapse Disorder...