I've got an interesting experience to add to this. About a decade ago, my father and I were going to the ranch to pick up some firewood for BBQ'ing. Before heading out of town we stopped at the local convenience store to get some fountain drinks. My father got a Diet Coke and I got a regular Coke.

When we got to the ranch we placed our drinks next to each other on the ground up against a tree. About and hour later, my drink had ants all over the lid and some managed to get inside the lid by the straw. My fathers Diet Coke didn't have a single ant on it.

Animals know. We're the stupid ones.