@Brand X,
Can you imagine an entire ant colony quitting work, and letting the queen and everyone else just curl up and die, because they were afraid they might encounter an enemy if they were seen working?
I can't. But, per Darwin, any such colony should be eliminated, for the good of ants everywhere.
When an ant dies, they don't bury it. They eat it. This gives them additional energy to forage for more food. It's a win-win proposition, caincha see?