Hygienic behaviour is the bees' ability to recognise diseased or dead brood, open the cell and remove it. It is heritable and it can be measured.

It is the single most useful indicator in breeding.

Why it matters so much

Colonies with strong hygienic behaviour:

• Are more resistant to chalkbrood and the foulbroods
• Partly limit Varroa reproduction by opening and cleaning infested brood
• Deal with problems before the beekeeper notices them

If only one trait is to be selected for, this is it.

The principle of the test

A small patch of sealed brood is killed and the time the colony takes to clean out those cells is recorded.

The measure is the proportion of cells cleaned. A colony clearing a high proportion within a set period is counted as hygienic.

Common methods

• Pin test: A set number of sealed cells are pierced with a fine needle. Simple and needs no equipment; adequate at small scale
• Freeze-killed brood test: A cut piece of comb is frozen and returned. More standardised but requires cutting comb

Whichever is chosen, keeping to the same method is essential for comparison.

Rules of application

• Mark the test area; it is hard to find afterwards
• Check at the end of the set period
• Test each colony more than once; a single measurement can mislead
• Test all colonies in the same period
• Forage and colony strength affect the result; test under similar conditions

Misleading situations

• A weak colony cleans slowly for want of bees; that is a strength problem, not genetics
• A break in forage can affect behaviour
• A new queen may not yet have set the colony's character

Using the result

Rear queens from the colonies scoring highest. Leave drone comb in the same colonies, so the drone pool in the area improves too.

Requeen the colonies scoring lowest.

A realistic expectation

Hygienic behaviour does not prevent disease entirely; it lowers the risk. It does not replace other measures but supports them.