Hi Margaret, thanks for the question.

These are boxelder bugs.  They can be drawn to the indoor warmth for overwintering. They can stain. Using pesticides inside is not suggested. Vacuuming them up is a good plan but don't use your indoor vacuum. Dispose of them immediately.  After they leave in spring, seal areas where they can enter you house. Check out the following links for more information:

Boxelder Bug (psu.edu)

Boxelder bugs | UMN Extension

Boxelder Bugs | Home & Garden Information Center (clemson.edu)

I hope this helps.