What can you see?

Despite their names, both European Foulbrood and American Foulbrood are present in the UK and are potentially so serious, that their presence in an apiary is notifiable by law. The National Bee Unit (NBU) is the authority charged with controlling foulbrood.

Beekeepers are legally obligated to report any suspected diseased colonies under the Bee Diseases and Pests Control Order 2006 (as amended).

If you suspect that you have Foulbrood, you must contact your local Inspector. Listed below are the identifiable features of each disease but if in doubt, the bee inspector must still be called; they will assist with identification and are always happy to help. There is a wealth of information on foulbrood including a downloadable leaflet and images on Beebase.

Most of the images on this page are from Beebase and Crown copyright applies. To download the images, please visit the Beebase image library.

Healthy brood

The most important thing, is to be able to identify healthy brood. Larvae should be a glistening ‘pearly’ white and should be lying at the base of the cell in a ‘c’ shape, the segments on their bodies clearly visible.

Capped brood should appear even, the cappings will have a dry appearance and may be a digestive biscuit colour however sometimes the cappings will be darker or more yellow depending on factors such as the age of the comb or the forage the bees have been working on. Anything that diverges from this description should be investigated further.

European Foulbrood (EFB)

EFB is caused by the bacterium Melissococcus plutonius. Larvae become infected by consuming contaminated food fed by the nurse bees. The bacteria multiply within the larval gut, competing with it for food. They remain in the gut and do not invade larval tissue; larvae that die from the disease do so because they have been starved of food. This normally occurs shortly before the cells are capped.

The identifiable symptoms are:

  • The disease affects larvae early; before they are capped. The ‘E’ in European stands for early
  • Younger larvae die and become transparent
  • Older larvae appear twisted (“melted down”), lose segmentation and turn yellow.
  • There may be a sour smell but not always. Beekeepers should therefore rely on their visual inspections.
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Provided the beekeeper has adequate equipment available, the bee inspector may conduct a whole apiary shook swarm to treat the outbreak.

For more information on European Foulbrood visit Beebase.

American Foul brood (paenibacillus larvae) AFB

Pepper pot brood pattern, darken, sunken cappings, some perforated.

AFB is caused by a spore forming bacterium called Paenibacillus larvae. These spores are the infective stage of the disease which begins when food contaminated with spores is fed to larvae by the nurse bees.

Once in the gut of the larva the spores germinate, bacteria move into the larval tissues, where they multiply enormously. Infected larvae normally die after the cell is sealed and millions of infective spores form in the larval remains. P. larvae spores remain viable for many years and are resistant to extremes of hot and cold and to disinfectants.

  • Only affects the pupal (capped) stage. The ‘A’ from American stands for after capping.
  • Pepper pot’ brood pattern
  • Perforated cappings. If you study the photograph, you’ll see tiny holes at the sides of some of the cappings where bees have attempted to uncap.
  • Moistened, sunken, darkened cappings
  • Roping when conducting a matchstick test
  • Scales visible on old comb
  • Unpleasant fishy smell (in more developed cases)

For more information on American Foulbrood, visit Beebase.

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