I've done some research on Colony Collapse Disorder which has become an increased epidemic starting in 2006, and I've found some interesting articles out there. Many of these articles mention a neonicotinoid insecticide called Clothianidin which is used on many crops in the United States, mainly corn. Clothianidin, once ingested orally, messes with the neurological state of insects and more specifically their motor function.
One specific study that I looked at took 96 Apis Mellifera honeybees from a hive of 7,000 and gave them varying amount of Clothianidin. The honeybees that were given a small dose were hyperactive, meaning that they had longer travel distances, decreased rest time, longer return to hive time, and more wild travel patterns in comparison to honeybees with no exposure to Clothianidin. Honeybees with a higher dosage had a much shorter flight distance, no rest time, slow movements, and a abnormal posture in comparison to honeybees with no exposure.
The study used high tech tracking cameras to observe the bees and this correlates directly with other research on Clothianidin that leads to Colony Collapse Disorder. When they honeybees travel longer with no rest time, or can't control their motor function because of their posture, they can't return to the hive and they die off. When they die off, the remaining honeybees in the hive overwork and they die from exhaustion leading to Colony Collapse Disorder.
Clothianidin is manufactured by the Bayer Corporation in Germany, the same people that make Bayer Aspirin. Germany has banned the use of Clothianidin on its crops because of its effects on bees, along with the UK. Now why haven't the United States banned the use of this harmful chemical?