What is this butterfly?

Good day.

This is a plum cocoonworm (Odonestis pruni) - a common inhabitant of our gardens, the caterpillar feeds on various deciduous trees, looks for shelter in the winter and in the spring after eating fresh foliage pupates, and in two weeks a butterfly comes out. How this creature ended up in your room - a caterpillar crawled in search of shelter for the winter, and because of the heat, it pupated and hatched prematurely. But the caterpillar still has to replenish its food supply in the spring - otherwise it may die, so it's rare that a butterfly has hatched. Maybe the second option-warming in winter-the caterpillar found some early tree and already ate climbed into the room. It would be interesting to know exactly what area you live in?

Such cases of insects appearing in rooms in winter are very common in villages among forests, steppes, where there are a lot of diverse animals, there are cases in megacities - insects do not need much - even a small park or flower bed can contain a lot of interesting animals.

Всього Найкращого, Віктор.

Thank you so much for the answer, I didn't even hope for it. The story is really strange, because I live in Moscow. I don't think it crawled in from somewhere, but it probably came with fruit from the store, though... But this is the only option, in winter there is unlikely to be another source of "xenobiota"