"Colony Collapse Disorder is an unknown condition that has all the worker bees in a colony to simply fly off as a group and never make a comeback to the hive. Scientists have been striving hard for years to unravel the mystery behind this odd phenomenon for years, but they are still not sure why it happens."
The bees are actually being abducted by aliens and forced to labor for alien queens.
hxxp://www.dailymail.co.uk/sciencetech/article-1323648/Bees-tiny-brains-able-beat-computers-complex-mathematical-problems.html