Lesson 83: Breeding for Mite Resistance

The traits that help bees fight varroa, and simple field tests to find your best colonies

Varroa mites are the biggest threat to honey bees (lesson 54), and treatments are a constant cost and concern. Breeding bees that resist mites is considered one of the best long-term answers. You don't need to be a professional breeder to take part: buying resistant stock, and choosing your best colonies to raise queens from (lesson 79), both move your apiary in the right direction.

The traits that fight mites

1. Hygienic behavior. Workers find and remove sick, damaged or dead brood from the brood nest. Hygienic colonies are more resistant to brood diseases like chalkbrood and American foulbrood, and remove some mite-infested brood too.

2. Varroa Sensitive Hygiene (VSH). A more specific form of hygiene: workers detect capped cells where mites are reproducing and open them and remove the pupa, interrupting the mites' reproduction. VSH colonies keep mite numbers lower without as much treatment.

3. Mite biting ("ankle biters" or "leg chewers"). Workers groom mites off themselves and each other and bite them, damaging the mites' legs and bodies so they die.

4. Suppressed mite reproduction. In some stocks, mites produce fewer offspring. Russian bees are known for this (lesson 15).

Resistant stocks you can buy include Russian, VSH, hygienic lines (for example, "Minnesota Hygienic" and others), and ankle-biter / leg-chewer lines. Russian and VSH stocks have also been shown to suppress viruses (lesson 62). No bee is 100% mite resistant, so keep counting mites (lesson 55) even with resistant stock.

Testing your own colonies

These tests help you find which colonies to raise queens from and which to requeen. Test the same way in every colony so results compare fairly, and test more than once.

Freeze-killed brood test (hygienic behavior)

1. Choose a frame with a large patch of capped brood (pupae with pink to light-purple eyes give the best comparison).
2. Kill a measured patch of brood by freezing. Researchers press a 2-inch metal ring (about 100 cells) into the comb and pour in liquid nitrogen. (Liquid nitrogen is −321°F and causes severe burns: it requires cryogenic gloves, safety glasses and covered skin.) A simpler home version is to cut out a small section of capped brood, freeze it in a freezer, and put it back (see the reviewer note).
3. Return the frame to the colony and mark it.
4. After 24 hours, count how many of the dead pupae the bees have removed.
5. A colony is hygienic if it removes at least 95% of the frozen brood within 24 hours, in two separate tests.

VSH test

Used mostly by breeders: - The queen must have been in the colony at least 7 weeks (so all bees are her daughters), with no recent mite treatments. - Using a frame with pupae 4–6 days after capping (white bodies, dark purple eyes), open 100 cells one by one with fine forceps and look for mites. A mite alone is non-reproducing; a mite family (a mother with a small white male and young females) is reproducing. - About 15% of mites fail to reproduce in normal colonies; a colony whose mites fail to reproduce much more often is showing VSH. A published chart turns the counts into a score from 0 to 4; breeders select queens scoring 4.

Mite-biting test

• Put an oiled insert under a screened bottom board and leave the colony undisturbed for 48 hours.
• Collect up to 100 fallen mites (need at least 10) and check each one under magnification for missing legs or damaged bodies.
• Colonies with at least 35% damaged mites are considered mite biters. Test twice in a season, when mite numbers are higher.

Simplest of all: keep records (lesson 41). The colonies that stay low in mites with little or no treatment, stay healthy and gentle, and produce well are the ones to raise queens from.

Putting it into practice

• Buy queens from breeders who test and select for resistance.
• Raise queens from your best colonies (lesson 79), and requeen your worst (lesson 45).
• Drones matter too. Queens mate with drones from many colonies nearby (lesson 13), so resistance builds faster when your whole apiary, and your neighbors', carries resistant genes (lesson 84).
• Be patient: breeding progress shows over several generations.

What to remember

• Resistance traits: hygienic behavior, VSH, mite biting, suppressed mite reproduction.
• Resistant stocks: Russian, VSH, hygienic, ankle-biter lines. None is 100%; keep monitoring mites.
• Hygienic test: freeze a patch of brood; ≥95% removed in 24 hours, twice.
• Mite-biting test: ≥35% damaged mites on a sticky insert.
• Breed from your best, requeen your worst, and buy from breeders who test.

Quick check

1. What does a Varroa Sensitive Hygiene worker do?
2. What result makes a colony "hygienic" in the freeze-killed brood test?
3. Why keep doing mite counts even with resistant stock?

Adapted from: Penn State Extension, Honey Bee Breeding Program Design series (Testing for Hygienic Behavior, Varroa Sensitive Hygiene, Mite Biting Trait Testing) and Varroa Mite Resistance series; Penn State Extension, Methods to Control Varroa Mites (2025) and Viruses in Honey Bees (2026); University of Arkansas, Complete Beekeeping Short Course, Part 11; Honey Bee Health Coalition, Tools for Varroa Management (9th ed., 2026).

Adapted from university Extension sources. Experienced Georgia beekeepers are reviewing these lessons. See something that doesn't match your experience? Tell us.