#2
In a guide to North American aquatic insects it best resembles
Bezzia. The book does not have an illustration of
Palpomyia, which is probably similar.
To definitively exclude Chironomidae you may need to examine the respiratory organs under a microscope.
#3
ID of Ceratopogonidae pupa to species level is impossible, to genus level difficult. The best way is to breed them and (try to) identify the adult. From this photo we can exclude Forcipomyia, Atrichopogon, Dasyhelea, Mallochohelea, Probezzia, Brachypogon, Stilobezzia (i.e. the known species of those genera). Next to Bezzia (suggested by John) some other genera may even be possible (e.g.Sphaeromias, Culicoides). The size may help for Sphaeromias has large representatives.
If you have the ability to buy or loan Tsalolikhin, S.J. (ed., 1999) Key to freshwater invertebrates of Russia and adjacent lands. Part 4: Diptera. St. Petersburg, Zoological Institute I advice you to do so.
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