European Foulbrood

European Foulbrood is caused by the melissococcus pluton bacteria.

European foulbrood is a highly contagious infection. It can remain without visible signs for a long period.

Age of brood affected

Unsealed brood of 3 to 5 days old in their ‘curled up’ phase are most vulnerable to infection. Some sealed brood may be affected.

Infection method

Bacteria is introduced to the larvae through infected honey. All bees may be affected by European foulbrood.


Symptoms of European foulbrood are:
  • Discoloured larvae. Larvae colour changes from glistening pearly white to:
    • yellow
    • light brown
    • dark brown.
  • Discoloured gutline. Healthy gutlines are golden brown or yellow. Infected larvae gutline will appear chalky white with yellow or white bands.
  • Sticky larvae liquid. Larvae will change from a watery to a sticky, then pasty consistency.
  • Dried dead larvae. Larvae will dry out. They can be easily removed from the cell wall once they are fully dried. This is a difference between European and American foulbrood.
  • Odor. The brood may develop a sour or foul odor if there is heavy infection.


Follow these steps to minimise the effects of European foulbrood:

  • Requeen regularly from disease-resistant stock.
  • Replace 2 or more brood nest combs annually with white combs or foundation. New hive material will help reduce the concentration of disease causing organisms.
  • Move bees at night. This reduces heat production and associated stress on the hive.
  • Make sure honey and pollen are good quality. Use artificial feeding if these aren’t available.

Antibiotics can be requested from a Primary Industries and Regions SA (PIRSA) Inspector. Only use antibiotics during a severe infection. Antibiotic residue in honey may affect market access.

Diagnosing European foulbrood

European foulbrood can be diagnosed by sending:

  • smears of diseased larvae on a microscope slide
  • sections of comb.

Send comb samples in a waterproof container.

Send samples to:

Apiary Unit
Primary Industries and Regions SA
33 Flemmington Street
Glenside SA 5065
Page Last Reviewed: 22 Feb 2018
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