Where have all the honeybees gone? A new study seems to strengthen the evidence linking pesticides used on crops to colony collapse disorder in honeybees. Colony collapse disorder, or CCD, is a phenomenon in which honeybees inexplicably disappear from their hives. The bodies of the dead bees are typically never found. Researchers led by Chensheng Lu of Harvard University have pinpointed the collapse of honeybee colonies on a class of pesticides known as neoniotinoids — insecticides that also act as nerve poisons and mimic the effects of nicotine. Scientists specifically looked at how low doses of two neoniotinoids — imidacloprid and clothianidin — affected healthy bee hives over the course of a winter. The results of the study “reinforce the conclusion that sub-lethal exposure to neonicotinoids is likely the main culprit for the occurrence of CCD,” the authors wrote in their paper, published May 9 in the Bulletin of Insectology. More