They will attract fruit flies and other insects, also the acidty in orange peel isn't a good idea.

Probably less of a problem with banana skins but they would still attract insects/fungus.

Best thing to do would be to make a compost heap in the garden/outdoors and chuck your peels in there and let them rot into the compost, untill your left with nice fresh compost that has been broken down properly and contains all the nutrients of the stuff you chucked in

Hope this has helped.