This is a brilliant piece of animation. I watched it as a child, and feeling nostalgic, bought a DVD with a collection of old cartoons (mainly because of this one), and watched "Зайчонок и муха" ("Little hare and a fly") 10 times at least since last Monday!
The story is simple: the little hare did not want to eat anything his mum gave him and threw the food out of the window. The fly who lived there, ate everything and grew very fast and troubled by the noise, "kidnapped" the naughty little one. She brought him food on condition his mum would give her food as tasty as she used to give her little son. All is well that ends well of course, and the naughty little one was taught a good lesson.
Click on the picture or the post title to see the cartoon :)
I think it a masterpiece. An instructive story told in an engaging way, with a lot of cute details and wonderful dubbing. It's from 1977 by the way.