If you prefer organic varroa mite treatments like we do, late fall/early winter, is a great time of year to use something like oxalic acid. While Oxalic Acid vaporizers work really well, you don’t have an expensive Oxalic Acid Vaporizer and can still easily do a late fall (or early winter) Oxalic Acid treatment to “clean up” some of the remaining mites on your colonies. Here’s an article from Betterbee, https://www.betterbee.com/instructions-and-resources/how-to-do-an-oxalic-acid-dribble-treatment.asp. One word of caution is that if you go with the Dribble you should only do one Oxalic Acid Dribble treatment in the fall, versus Oxalic Acid Vapor, where it is fine to do more than one. Also, here is a video on the Oxalic Acid Dribble (note the video is in Canada, so you’ll want to take that into account when they say it’s their final treatment and are wrapping things up for the year). https://www.youtube.com/watch?v=sdScP69gzhE