Unlike adult bee diseases, brood diseases are visible. An experienced eye looking at the comb can tell most of them apart.

Regular brood inspection is therefore the single most informative act in bee health.

The main diseases

• American foulbrood: A spore-forming bacterium; the most destructive
• European foulbrood: The larva dies before the cell is capped
• Chalkbrood: A fungus; the larva turns into a chalky mummy
• Stonebrood: A different fungus; the mummies are harder and greenish
• Sacbrood: A virus; the larva becomes a fluid-filled sac

Telling them apart

Three of these are confused with one another and their consequences are very different:

• Matchstick test: In American foulbrood the remains stretch out like a thread for two or three centimetres. In the others they do not
• Scale: In American foulbrood it adheres firmly to the cell and cannot be removed without scraping. In the others it lifts out easily
• Smell: Sharp and foul in the foulbroods. Sacbrood has no smell
• Time of death: After capping in American, before capping in European

Definitive identification is made with a field kit or laboratory analysis.

General signs

• Irregular, patchy brood pattern
• Sunken, perforated or greasy-looking cappings
• Discoloured larvae
• Discarded brood or mummies in front of the entrance

Reporting obligations

The foulbroods are notifiable in many countries. If suspected:

• Close the hive; stop moving comb and equipment
• Document it: photographs, date, hive number
• Inform the competent agricultural authority or your beekeeping association
• Do not apply antibiotics on your own; they do not kill spores, they conceal symptoms and they leave residues

Prevention

• Renew comb regularly
• Clean the hive tool between hives
• Do not move comb between colonies at random
• Do not buy colonies, comb or honey from unknown sources
• Work with lines showing strong hygienic behaviour
• Keep colonies strong and well fed