The Tale of Tsar Saltan (1943)

The story is about three sisters. The youngest is chosen by Tsar Saltan to be his wife. He orders the other two sisters to be his royal cook and weaver. They become jealous of their younger sister. When the tsar goes off to war, the tsaritsa gives birth to a son, Prince Gvidon (Gvidón.) The older sisters arrange to have the tsaritsa and the child sealed in a barrel and thrown into the sea. The sea takes pity on them and casts them on the shore of a remote island, Buyan. The son, having quickly grown while in the barrel, goes hunting. He ends up saving an enchanted swan from a kite bird. The swan creates a city for Prince Gvidon to rule, but he is homesick, so the swan turns him into a mosquito to help him. In this guise, he visits Tsar Saltan's court, where he stings his aunt in the eye and escapes. Back in his realm, the swan gives Gvidon a magical squirrel. But he continues to pine for home, so the swan transforms him again, this time into a fly.

Unfortunately the movie The Tale of Tsar Saltan is not yet available on Disney Plus.