I had tomato plants outdoors in containers that I brought indoors before the 1st frost,but they were infested with whitefly.
I left them on a unheated porch windowsill until the temps dropped down into the low 30's F
Low enough to kill the critters but not the plants.
Then I brought them indoors.
Ditto for the pepper plants that had spider mites.
So I won the battle without using any chemicals or manual labor.
In the past I had them on electric food warming trays but in this episode I was conserving electricity.