So you think you need to treat again (or maybe you haven’t done so before). If you’re wondering if you still can, the answer is yes! Although late summer treatment is the best for protecting your winter bees, a delayed treatment is better than no treatment.

Whenever you need to treat for varroa, you have to consider which treatment is the best for the time of year and the status of your hive.

  • 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

Active Ingredient
Temperature Range
Length of Treatment
Supers On or Off?
(dribble or vaporization)
Oxalic acid As low as 40 deg. F Single dose Off 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 makes opening the hive impossible.
Formic Pro™ Formic acid 50-85 deg. F 14 or 20 days On Best used earlier in the fall, rather than later.

All of these factors need to be taken into account when choosing a treatment method, but particularly so 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. 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 - right now.