Just found ants in my six-spotteds, too...
I HATE ants. They go after the roach food/dead ones/poo/whatever they can eat. I've vacuumed the little monsters up, cleaned out the bin, washed off the outside to get rid of the scent trail, and they still come back! Can't spray, obviously, but some people are using double sided tape around the container to discourage the scouts. Try to find the place where they're coming into your house and do some spot-spraying. It's a never-ending battle.