I'm finding some kind of little gnat in mine that aren't there in summer. Some drowned and floating, but a few under the lid of my saucer style feeders. I'm opening them outdoors these days, before I bring them in to clean and refill.

A couple of weeks ago I released gnats at my kitchen sink taking off the lids, which led to squashing them with a paper towel against the kitchen window over the sink, then having to wash the window. I don't mind the feeder chore, but really don't need to make more work for myself than that.