I would try diatomaceous earth under or around the bin since the ants are probably coming and going from the bin. If you have the bin raised (most people do that for drainage), under would be best.

Also, if there is a particular food you have been adding to your bin that the ants are attracted to, try withholding it for a while. I guess that is pretty obvious, but maybe you haven't been thinking along that line. Good luck. I wouldn't want ants in my bin, even though they are harmless.

How dry is it? Ants like it dry so adding some water may help??

I thinnk one of my compost bins has turned itself into a worm bin! It is full of red wigglers and when I go to turn it, I'm slicing the poor things. So I left it alone for a while and it seemed to be doing ok, turning itself into soil. Then DH put a big bucket of kitchen trimmings into it and once again the worms are all over it, crawling up the sides onto the lid. Plus flies. He doesn't cover stuff with dried leaves or shredded paper. How do you harvest the soil with a worm bin?

Dottie,
Harvesting the worm castings is always a sticky wicket. What I would do in your situation, is this. I would pick out a bunch of those red wigglers and start a proper worm bin. See the vermicomposting forum for how to do that. Setting aside a cup or two of them for the new bin would be enough because they will reproduce quickly, especially in warm weather, but the more the merrier. Then I would just apply the worm compost to your soil, or mix with potting soil, mix with water and pour it around your plants, whatever you want. You can also put it in some containers or plastic bags and it will keep for quite a while.

The advantage of a proper bin over your informal method is that you could harvest the castings more easily. I created my own very unorthodox method which is super easy. I put all the new food in net bags and have a whole bunch of wine corks under the bags for drainage/bedding. I have shredded newspaper on top to help regulate moisture and temp. To harvest, I set aside the shredded newspaper and net bags, dump the corks, which are covered in worm poo, into a bucket, add water, remove the floating corks and put them back in the bin, and pour the 'tea' on my plants. They really like it.