Two widely used neonicotinoids — a class of insecticide — appear to significantly harm honey bee colonies over the winter, particularly during colder winters, according to researchers. The study replicated a 2012 finding from the same research group that found a link between imidacloprid and Colony Collapse Disorder, in which bees abandon their hives over the winter and eventually die. The new study found low doses of a second neonicotinoid, clothianidin, had the same negative effect.