Understanding British Bee Diseases: A Practical Guide for UK Beekeepers
Beekeeping in Britain carries a long and distinguished history, with records of managed colonies stretching back to the medieval monasteries of rural England. Today, the British Beekeepers Association (BBKA) estimates there are around 44,000 registered beekeepers across England and Wales, tending everything from single hives in suburban back gardens to large-scale apiaries across the Yorkshire Dales and Scottish Highlands. Whether you manage one National Hive or fifty, understanding the diseases that threaten your colonies is not merely advisable — it is a legal and ethical responsibility.
British bees face a formidable range of threats. Some diseases are ancient, having plagued colonies for centuries. Others, such as those introduced via the global trade in bees and equipment, are relatively recent arrivals to our shores. The British climate — damp, mild winters and unpredictable summers — creates particular conditions that can encourage the spread of certain pathogens. Knowing what to look for, how to report it, and what practical steps to take is the foundation of sound beekeeping practice.
The Legal Framework: What UK Beekeepers Must Know
Before examining specific diseases, it is worth understanding the regulatory context in which British beekeepers operate. In England and Wales, bee diseases are governed primarily by the Bee Diseases and Pests Control (England) Order 2006 and equivalent legislation in Scotland and Wales. These regulations place a statutory duty on beekeepers to report certain notifiable diseases and pests to the Animal and Plant Health Agency (APHA).
The National Bee Unit (NBU), which operates under APHA, employs a network of seasonal and regional Bee Inspectors whose job is to visit apiaries, conduct inspections, and assist beekeepers in diagnosing and managing disease. Their free BeeBase registration system (available at nationalbeeunit.com) allows beekeepers to register their hives, receive alerts about disease outbreaks in their area, and request inspections. Registration is strongly encouraged by the BBKA and is entirely free of charge.
Notifiable diseases and pests — those that must by law be reported to a Bee Inspector immediately — currently include American Foulbrood, European Foulbrood (in some circumstances), Small Hive Beetle, and Tropilaelaps mites. Failure to report these can result in legal action and, more importantly, allows disease to spread unchecked through neighbouring apiaries.
American Foulbrood: The Most Feared Disease in British Beekeeping
American Foulbrood (AFB), caused by the spore-forming bacterium Paenibacillus larvae, is the most destructive bacterial disease of honey bee brood in the world, and it remains a serious concern for British beekeepers. Despite its name, it is far from confined to North America — outbreaks occur regularly across England, Scotland, and Wales.
The disease attacks larvae after they have been sealed in their cells. The spores are incredibly resilient, capable of surviving in old equipment, honey, and wax for decades. A single cell of diseased brood can contain billions of spores. This persistence is what makes AFB so dangerous and so feared.
Recognising American Foulbrood
The signs of AFB are distinctive once you know what to look for:
- Sunken, discoloured, and often perforated cappings over brood cells
- A strong, characteristic smell often described as rotting fish or decaying flesh
- The “ropiness test” — inserting a matchstick into a cell and withdrawing it slowly will draw out a brown, stringy rope of infected material that stretches to approximately 2–3 centimetres before snapping
- Dried scales of dead larvae adhering tightly to the lower wall of cells — these are extremely difficult to remove and a reliable diagnostic indicator
- A “shotgun” brood pattern as the colony struggles and nurse bees attempt to clean out infected cells
If you suspect AFB, do not attempt to treat it yourself. Stop all inspections immediately and contact your local Bee Inspector via BeeBase. AFB is a notifiable disease and the legal requirement is clear. In the majority of UK cases, affected colonies and their equipment must be destroyed by burning. There is no licensed treatment for AFB available to UK beekeepers — the use of antibiotics to treat or suppress AFB is illegal in Britain, unlike in some other countries.
European Foulbrood: A Growing Concern
European Foulbrood (EFB), caused by the bacterium Melissococcus plutonius, is in many respects a more complex disease than its American counterpart, partly because its presentation can vary considerably and because the relationship between colony health and disease severity is more nuanced.
EFB attacks younger, unsealed larvae, typically between four and six days old. Unlike AFB, it does not form the same persistent, decades-long spores, but it is nonetheless a serious threat — particularly in seasons when colonies are nutritionally stressed, which in Britain often means the weeks following a cold, wet spring.
Recognising European Foulbrood
- Larvae appear twisted, melted, or slumped in their cells rather than lying in the characteristic C-shape of healthy brood
- Colour changes from pearly white to yellow, brown, or in severe cases almost black
- A sour or vinegary smell, less pungent than AFB but still noticeable
- Larvae die before the cells are capped, so sunken cappings are not typically a feature
- In advanced cases, a dried, rubbery scale remains — less tightly adhered than the AFB scale and more easily removed
EFB is also notifiable in England and Wales under the 2006 Order. Bee Inspectors will assess the severity of the infection and may prescribe treatment with the antibiotic oxytetracycline (via a veterinary prescription under the cascade system), though this is only available in limited circumstances. In severe outbreaks, destruction of the colony may be required. Milder cases in strong colonies sometimes resolve naturally once conditions improve and the colony’s nutritional status is addressed through supplementary feeding.
Varroa: The Persistent Parasite That Changed British Beekeeping Forever
The arrival of Varroa destructor in Britain — first confirmed in Devon in 1992 — transformed British beekeeping permanently. This external parasitic mite, originally a parasite of the Asian honey bee Apis cerana, had no natural resistance in Apis mellifera populations and spread rapidly across England and Wales throughout the 1990s. Today, Varroa is present in virtually every managed colony in mainland Britain. The only significant exception is a number of remote Scottish islands, including parts of the Outer Hebrides, which remain Varroa-free and are carefully monitored to protect this status.
Varroa mites reproduce inside sealed brood cells, feeding on the developing pupa’s fat body. The damage caused is twofold: direct physical harm from feeding, and the transmission of multiple bee viruses, most notably Deformed Wing Virus (DWV), which is now ubiquitous in British bee populations and causes stunted wings, shortened abdomens, and severely reduced lifespan in affected bees.
Monitoring and Managing Varroa
Effective Varroa management requires a year-round, integrated approach. Key practices include:
- Regular mite counts using sticky boards or alcohol wash/sugar roll methods to determine infestation levels
- Brood breaks — either natural (swarm) or artificially induced — which interrupt mite reproduction and allow treatments to work more effectively on phoretic (non-reproductive) mites
- Approved treatments including oxalic acid (applied by trickle, sublimation, or extended-release strips), thymol-based products such as Apiguard and Apibioxal, and synthetic miticides such as Apivar (amitraz) and Bayvarol or Apistan (pyrethroids, though widespread resistance is now a significant problem in Britain)
- Rotation of treatments to minimise the development of resistance
The NBU publishes detailed guidance on treatment thresholds and timing, and the BBKA offers training courses specifically focused on Varroa management. Many local beekeeping associations, from the Devon Beekeepers Association to the Scottish Beekeepers’ Association, run practical workshops where members can learn mite-counting techniques firsthand.
Nosema: A Gut Disease with Seasonal Patterns
Nosema is a fungal gut disease caused by microsporidian parasites. Two species affect British honey bees: Nosema apis, which has been present in Britain for well over a century, and the more recently identified Nosema ceranae, which is now thought to be the more prevalent species in many UK apiaries.
Nosema apis classically causes dysentery in the spring, particularly following a long, cold winter during which bees have been unable to fly to take cleansing flights. Affected bees produce brown faecal streaking on the front of the hive, the landing board, and surrounding vegetation. Nosema ceranae, by contrast, tends to be more chronic, causing colony decline without the obvious dysentery symptoms, making it harder to detect.
Diagnosis requires microscopic examination of bee gut tissue, and the NBU can assist with this. Fumagillin, formerly the standard treatment for Nosema, is no longer authorised for use in the UK or the wider European Union. Management therefore focuses on good husbandry: ensuring colonies overwinter on clean comb where possible, replacing old brood comb regularly (the “Bailey comb change” is a well-established British technique), maintaining strong colonies going into autumn, and ensuring adequate ventilation in the hive to reduce condensation — a particular concern given British winter conditions.
Moving Forward
Once you have the fundamentals in place, the possibilities open up considerably. The UK offers fantastic opportunities for anyone interested in this hobby, and with the right foundation you will be well placed to make the most of them.