A honey bee colony is not just a collection of individual bees – it is a "superorganism" that can defend itself against disease. One of the most powerful and at the same time most natural defence mechanisms is hygienic behaviour (the cleaning drive): the ability of workers to quickly detect and remove diseased or dead brood before it becomes a source of infection for the whole colony. This article explains why the trait is worth measuring, how it relates to genetics and breeding, and what it concretely brings to a beekeeper who starts to measure it deliberately.
What hygienic behaviour is and how it works
Technically we speak of behavioural resistance – resistance conditioned by the bees' behaviour rather than by an immune reaction in the strict sense. Workers with developed hygienic behaviour constantly "inspect" the brood. As soon as they sense that a pupa under the capping is dying or is infected, a two-phase behaviour appears:
- Uncapping – the bees open the capping of the suspect cell.
- Removal – they carry the non-viable pupa out of the hive.
What matters is speed. Disease agents (fungi, bacteria) need time to mature in the dead brood and form resistant spores. When the bees clear them out early enough, the infection cycle is broken before infectious material can form. A slow colony, by contrast, lets the spores mature and the disease spreads further.
What hygienic behaviour specifically helps against
Strong hygienic behaviour is associated with resistance to a whole group of brood diseases and to the Varroa mite:
Chalkbrood (ascosphaerosis)
The most closely linked disease. The fungus Ascosphaera apis turns larvae into hard "mummies". Hygienic colonies remove them so quickly that the disease practically does not show – whereas weak colonies lose brood, strength and honey yield and must invest energy into replacing the dead brood.
Foulbrood
With bacterial foulbroods, the early removal of diseased larvae is crucial: it prevents the formation of an enormous number of extremely resistant spores that survive for many years. Here hygienic behaviour acts preventively at the level of the whole colony.
Varroosis and the VSH trait
A special form of hygienic behaviour, so-called VSH (Varroa Sensitive Hygiene), targets the sealed brood infested by the mite directly. The bees recognise cells in which the mite is reproducing, uncap them and disrupt its reproductive cycle. VSH is today one of the main directions in breeding bees resistant to varroa – a way to reduce dependence on chemical treatment.
Viral infections
By removing weakened and non-viable brood, the reservoir of viruses in the hive is also reduced (many of them spread precisely via the mite and diseased brood). A healthier brood nest means lower overall pathogen pressure.
Why it matters – in short
- Fewer brood diseases without outside intervention.
- Lower need for medication and chemicals → cleaner honey and wax.
- Stronger, more even colonies and more stable yields.
- The basis for breeding resistant to varroa (VSH).
Heredity and genetics: why hygienic behaviour can be bred for
Hygienic behaviour is not chance nor just a matter of "luck with the weather" – it is an inherited trait. It is under genetic control (a trait influenced by several genes, a so-called polygenic trait) and can therefore be increased deliberately through selection. This is crucial for the breeder: a trait we can measure we can also improve.
The principle is the same as for any other breeding:
- Measure – objectively test the hygienic behaviour of individual colonies (this is what the pin test is for).
- Select – use queens from the colonies that clear the brood fastest and reliably throughout the season for further breeding.
- Fix – consolidate the trait through controlled queen rearing, and in advanced practice through insemination, so that it is passed on to the offspring.
Because it is a polygenic trait, the results add up gradually: each generation selected by a measurable number moves the whole stock towards greater resistance. International breeding programmes (e.g. lines selected for VSH) show that in this way the natural resistance of bees can be increased significantly within a few years.
What it brings to breeding in practice
A stock built on resistant lines is more sustainable and cheaper to maintain. Healthier colonies overwinter better, collapse less and give more stable yields. Reducing the need for chemical intervention also improves the quality of honey and wax and matches the growing demand for natural, gentle beekeeping.
It is important to stay realistic: hygienic behaviour is a necessary but not the only condition for health. Even an excellently hygienic colony needs a good site, sufficient forage and reasonable care. Under heavy varroa pressure it is still appropriate to monitor the mite drop and treat if needed – hygienic behaviour lowers the pressure but on its own may not be enough under extreme conditions.
Why PinTest specifically
For a measurement to make sense it must be standardised, fast and repeatable – otherwise colonies cannot be compared fairly with one another. This is exactly what the PinTest tool solves:
- Standardisation: a needle stamp with 50 needles kills a precisely defined area of brood always in the same way – comparably for every colony.
- Speed: one press tests 50 cells (for 100 you press twice). You manage the test during a single visit to the apiary.
- An objective number: from the number of cells cleared over time a single value (HT) is calculated – how many hours on average it takes to clear one cell. A lower number = better hygienic behaviour.
- Comparability: the same method and the same number let you rank colonies and track the progress of the stock year after year.
You do not have to calculate the result by hand – you enter the values from the checks into our online calculator and it returns the HT value and a verbal rating of the colony. You will find the detailed procedure on the Method page.
How to read the results – and what to do with them
A single excellent result is not yet a guarantee. The result is affected by colony strength, weather, the season phase and queen age. Therefore:
- Repeat the test on promising colonies – ideally several times per season.
- For breeding, choose colonies that keep good hygienic activity long-term, not just once.
- Rear queens from the best and consolidate the trait deliberately.
Measure the hygienic behaviour of your colonies
From an impression to an objective number. The tool and the calculator are ready.
Sources and further reading
This article is based on generally accepted knowledge about the hygienic behaviour of bees and its use in breeding. For deeper study we recommend:
- SARE – Testing Honey Bee Colonies for Hygienic Behavior (methodology and significance of hygienic behaviour tests).
- Scientific work on Varroa Sensitive Hygiene (VSH) and breeding bees resistant to varroa.
- Studies on the relationship between hygienic behaviour and resistance to chalkbrood (ascosphaerosis) and foulbrood.
- Review articles on the heritability of hygienic behaviour and its use in breeding programmes.
Note: This text is informational and does not replace veterinary advice. If you suspect a legally regulated disease (e.g. American foulbrood), follow the applicable regulations and the instructions of the competent authorities.