Worm composting - fruit flies?

Anyone out there have a worm compost bin and get fruit flies? This time it wasn't even from bananas, I think it was from the soil I was using for an experiment for my online course! But the house is infested again and when I went to put in some corn husks today the poker I use to move the material around was covered in what I'm pretty sure was little fruit fly grubs (or whatever they're called). Made my skin crawl. I put the bin outside, and it's staying out there for a week. I'm also cleaning everything wet or raw in the house and drying the sinks before I go away for around 5 days! Any other, less drastic, ideas?