Though the mass deaths of the bees took place in September, USDA made its findings public this month. It is, however, not known how the bees consumed the poisonous substance.
The US Department of Agriculture has concluded an investigation into the death of roughly three million honeybees at a sanctuary in California - and results suggest the deaths were deliberate.
What killed 3 million honey bees around San Diego? Beekeepers fear the answer has larger ramifications columbian.com - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from columbian.com Daily Mail and Mail on Sunday newspapers.