These things are a microscopic menace! We call them no-see-um’s. They have a worldwide distribution, unfortunately:
One good thing is, in North America and Europe, they don’t transmit diseases to humans.
Here in Calgary, people will say “The bugs are terrible today!”, and either:
- They’re not even biting insects; these people are just freaked out by male mating swarms
- Or there are a few mosquitoes, which I don’t even notice, as my body is used to them
But I was in Manila, and no-see-ums were causing huge welts all over my body (which is an immune reaction to the anticoagulants and enzymes in their saliva). You wonder if you’re going crazy, because you don’t see anything biting you. They’re like a speck of dust in the sunlight.
With regard to Question 4: How to keep them away?, here are a couple of threads about insect repellents:
https://forum.inaturalist.org/t/natural-insect-repellents/
https://forum.inaturalist.org/t/neem-for-ticks-mosquitos/
Viel Glück mit den Gfrastern, Erwin!