Same joke appears in post #7794758 and post #7915500. Google turns up this 2015 tweet, indicating that a) the joke is pretty old and b) the specific size is surprisingly consistent.
Pretty strange that ants aren't really picky about it, keep seeing ants swarming on chocolate even it will kill them-
Depends on the concentration, really. It's also a good way to test your instant coffee if they're straight up fake (made with flavoring) or decaf: ants will still swarm to a sweetened coffee under certain concentration of caffeine. In fact, they actually works and learn faster with low doses of caffeine, much like we do!
