Hi Cathy2,
Like Laikom, I am just using small open bowls which I place near our bananas. In the past, I have tried Kenny's suggestion which involves poking small holes in plastic wrap and covering the bowls. I now just skip the plastic because it is faster.
Based on the number of flies in the bowl, I don't thinking many fruit flies are escaping from the apple cider/dawn mixture (though I've never stopped to observe them

)
Without using a cover, I can quickly dump the cider solution, rinse the bowl and repeat. Right now, things are fine because I froze my over-ripe bananas.
( I wanted to link to banana bread recipe which I thought I found on LTH, but now I can’t find. It called for cooking down the banana-liquid and the recipe used many more bananas than another other recipe I’ve seen. As a side note, if you know where to find this great recipe, please send me link. )