It's either proplylene glycol or methanol, depends on the brand of antifreeze. Probably proplyne glycol, if bees like it. The stuff is used to sweeten toothpaste, mouthwash, etc. Not harmfull itself, but they add anti corrosives to it, reactive coppers and chromiums, those will mess up your liver and kidneys. Could put a dent in your bee population in a few weeks, but they couldn't have picked up much if it was spilled on soil, and you washed it away quickly.