When it gets cold in the midwest, small mites and stuff will naturally find their way into houses seeking warmth, and vegetation that isnt dying.
Back in Kansas, iowa, nebraska, etc, if you arent doing preventative treatments as the weather turns cold, you will be almost guaranteed to end up with russet or spider mites on your indoor plants unless theres a good sized gap between your grow environment and any potential source of them coming inside the house. A big offender is bringing tropical potted plants in for the winter without treating them.
At least that was my experience in the midwest.