Most ants won't bother the worms at all, though they will eat some of their food. The exception seems to be fire ants, who will at times kill worms. If they don't bother you, chances are they won't bother the worms.

Dick

I have always read that ants are a sign of dry conditions. I, in 5 years, have never seen any ants in or around my bins, although they are elsewhere in some dry leaf piles I have.

Right after we started 4 new bins, fire ants showed up in three of them. Not really a surprise as we have them in all the other compost piles. I made it a point to stir up the bins and disrupt each one thoroughly at least once a week; and within two weeks all ants vacated the bins on their own accord.

As regular maintence I like to dig around and check the each bin throughly to find any problem spots or unwanted guests. The worms don't seem to mind--however we do try to limit opening the bins to once a week maximum.

Pura Vida

Here is a link that might be useful: Garden Picture Blog

After years of "worming", I had a massive invasion of ants a few days after I put my kids' uneaten gingerbread house into the bin. Got rid of them by by removing as much of the gingerbread as I could, flushing the whole system with water, letting it drain and dry for a couple of days uncovered, and then reassembling with a lot of new dry bedding. I don't know if the ants would hurt the worms, but I couldn't open the bin without getting covered by them.

Oh..and one other thing I learned..Ants do not like coffee grounds. The grounds will not kill them but they will leave.