There seems to be a biting insect outbreak going on. After a brave soul actually brought some in, and a little bit of research, it seems these are biting midges. They also are called biting gnats, punkies, no-see-ums, and worse.

Like anything in the biting fly family, they are hard to control. They don't need standing water to develop in, they aren't dawn and dusk feeders like mosquitos, and they don't "roost" in a particular area. They are also small enough to come through many window screens. And when they bite, they leave a painful welt. Smaller screen wire size will help keep them from entering the home, as will keeping windows shut. Using "bug light" bulbs will also attract fewer, as will the sodium lights outside.