Sometimes written as “Noseeums” to make it all one word. This is a good common name, because while you “feel-um” (they feel like a tiny itchy pinprick), you don’t “see-um”. Like this one on Sam’s arm:
The story was, Sandy was out in the yard on August 4, 2012 practicing building decorative stonework structures, and came in telling us that the no-see-ums were really bad in that particular spot. So Sam and I went out there and waited a bit for one of us to get a bite. Sam felt one first. I managed to get a couple of pictures, but then Sam said it itched too much and scratched it away. So, I waited until I got a bite, and tried to get pictures of that:
But now I had two problems: (1) I couldn’t contort around to get a picture with one hand of something resting on my other arm, so I had to have Sandy take the picture of an insect she couldn’t see through the viewfinder while I pointed out where it was; and (2) more seriously, my arm hair was too thick and obscured the view. At any rate, from my fingertip you can see that this little bugger was only about a millimeter long, and barely visible to the naked eye.
So finally, Sandy went out again, and after a while came running into the house saying “I’ve got one, but hurry, it itches like crazy!” So we propped up her arm for stability, she pointed out where it was, and I finally spotted it well enough to get some photos.
(the pictures are a bit blurry and small because the no-see-ums were so tiny, and I cropped the images pretty heavily)
At which point Sandy finally said, “That’s enough!”, squished it, and then scratched vigorously.
These were all probably biting midges in the family Ceratopogonidae, pretty much all of which are tiny and only a few of which bite mammals like us – most of them bite birds, or reptiles, or amphibians, or larger insects. The larvae live in mud and wet sand around marshy areas. The adults are easily small enough to slip through window screens, although the finer mesh of the “bug baffler” suits seems to stop them. Luckily, while they do itch while they are biting you, the ones we have locally don’t seem to raise the big, long-lived welts that their more-annoying relatives the Black Flies often cause. Although, I understand there are some species further south that do raise such welts.
 We have a lot of stones available, since our property is all glacial till from the last ice age, and the soil runs probably around 30% stones by volume. So Sandy has been experimenting with using our rich rock crop to build structures like retaining walls and pillars. Ultimately, her goal is to make fancier things like decorative facades on the house, free-standing walls, and stone foot-bridges. The main issues are that our local stones mostly aren’t very pretty, and tend to be rounded (and therefore hard to stack) due to being tumbled by the glaciers. It’s a lot easier to build stone structures with flat stones, which are a bit harder to find. Although, there are some spots where our road cuts through some nice fine-grained sandstone that tends to break off in flat slabs, and she likes those stones better for building than the rounded ones.
 I like my bug-baffler suit. I mainly use it to minimize getting stung when I open up the beehives, but it also works great when I’m going into areas that are infested with biting insects. It even gives some protection against getting poked in the eyes by tree branches when walking in the woods. The only downside is that it does restrict the air from blowing over my skin, so it can get pretty hot on sunny summer days.