Question
Is there a plant that would survive in a south facing window in zone 5  that would consume fruit flies?

Answer
Hi Ann,

If your South Facing window is nice and sunny, a Cape Sundew (Drosera capensis) or a Fork-Leaf Sundew (Drosera binata species) are excellent options for a fruit fly catcher.  Here's a link to care of tropical sundews:  http://www.growcarnivorousplants.com/Articles.asp?ID=262

Good Growing!

Jeff Dallas
Sarracenia Northwest
http://www.growcarnivorousplants.com