If it’s already fall and you need to treat for varroa mites again, or maybe for the first time, you may be wondering if you still can — and the answer is yes! Deciding whether your hive needs mite treatment is the first step. After completing a mite count, consider the time of year and your local climate to figure out which varroa mite treatment is best for you.

When is it too late to treat for varroa mites?

So, how late can you treat for varroa mites? Although late summer treatment (probably following a mid-summer treatment) is the best way to protect your winter bees, a delayed treatment in late fall is better than no treatment at all. However, you may use different varroa treatment options depending on the time of year and the status of your hive.

When you’re choosing the best varroa mite treatment in fall, consider that:

  • Some treatments have high or low temperature limits.
  • Some treatments can't be used when you are collecting honey.
  • Some treatments aren't effective when there is a lot of brood in the hive.
  • Some treatments use more (or less) synthetic chemicals.
  • Some treatments require special equipment or personal protective gear.
  • Some treatments are highly effective and some are not.

Late Season Varroa Mite Treatment Options

Product
Active Ingredient
Temperature Range
Length of Treatment
Supers On or Off?
Notes
(dribble or vaporization)
Oxalic acid As low as 40 deg. F Single dose On For best results hive should be broodless, or nearly so. Requires special equipment to use as a dribble and during vaporization.
Thymol 60-100 deg. F 28 days Off More effective in warmer weather (70-85 deg. F) when bees are not in a constant cluster.
Amitraz n/a 42 - 56 days Off Must be installed early enough in the fall so that the strips can be removed at the end of the treatment before winter weather makes it harder to get in and out of your hives.
Formic Pro™ Formic acid 50-85 deg. F 14 or 20 days On Best used earlier in the fall, rather than later.
Hops beta acids Daytime temps above 50 deg. F 14 days On As with oxalic acid, works best when there is little to no brood in the hive so mites have no refuge from treatment.

All of these factors need to be taken into account when choosing a treatment method, especially at the tail end of the season when temperatures are changing rapidly. That's why it's impossible to say which treatment is best for every beekeeper in the fall — the answer depends on too many factors to provide a single ideal option.

If you need help sorting all these factors out, we'll be glad to help. Please call our Customer Service staff at (800) 632-3379 for expert advice about the best options for your hives in your area. For more beekeeping tips and advice, explore our Beekeeper Guide.