Tomatoes

I just started vege gardening this year. I tried square foot gardening. My tomatoes, along with cucumbers and peppers are wonderful. I do have one problem though. As soon as a tomato gets ripe I go to pick it and the back side has been completely eaten away by little gnat looking bugs. Help! Can I spray them with soapy water or something? The tomatoes look so beautiful on the front side I would realy like my husband and I to enjoy them! Thanks!