Honey Bee Diseases

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The goal of every beekeeper (myself included) is to reduce the effects of honey bee diseases in their hives. Like any living thing, our bees do fall prey to various types of pathogens which can cause colony failure. Striving to reduce the prevalence and persistence of disease promotes healthy productive honey bees.

Diseased dead honey bees laying on wooden floor.

Good beehive management begins with regular inspections of the hive. You can not combat disease problems without knowing what is happening inside the brood nest area.

Diseases that Affect Bee Colonies

Diseases that affect honey bee colonies can generally be divided into 2 categories. Those that affect bee brood – (the development part of the honey bee life cycle) and those that attack adult bees.

Both can cause great harm to the hive – resulting in low populations, poor performance and even colony death.

Healthy brood in a honey bee hive.

Brood Diseases

Brood diseases are some of the easiest ones for an average beekeeper to identify. They affect the bee larvae and pupa developing in the brood nest.

There will not always be a cure for these problems in your hives. However, you should be able to recognize the symptoms of each – and take action if needed.

  • American foulbrood (Paenibacillus larvae = Bacillus larvae)
  • European foulbrood (Melissococcus pluton)
  • Chalkbrood
  • Sacbrood

The Foulbroods

Beekeepers must be on the watch for two kinds of foulbrood disease – though they share a common name – there are important differences. One may clear up on its own – the other is often a death sentence for a colony.

American foulbrood (AFB) is one of the most dreaded of honey bee diseases. It is a highly contagious bacterial disease that attacks mainly bee larvae.

A severe threat to the colony (even the whole apiary) – diagnosis and treatment or destruction of the colony is imperative.

European foulbrood (EFB) is also caused by a bacteria. It too affects the larval stage of bees but is not as severe as AFB.

While it can weaken a colony, this form of brood disease often clears up on its own when foraging conditions improve.


Both types of foulbrood presents as discolored brood – larvae that are dark, or brown (instead of white).

In AFB, beekeepers detect a dead animal smell and bee brood remains that are very ropy with hard scale in the cells.

Whereas, EFB is less ropy with no hard scales remaining in the cells. The smell is said to be more sour – but in my beehives – all dead brood smells awful to me – I can’t detect a difference by scent.


Chalkbrood is caused by a fungus (Ascophaera apis). The symptoms are white or black mummies (brood) in wax cells or loose on the hive floor.

You may see these mummies on the ground outside the hive entrance if the workers are trying to discard them.

This is a stress disease that appears when things are not at optimum levels for the colony. Chilling brood during cold weather is one cause. Keeping healthy, strong colonies is the best defense.


The honey bee disease known as Sacbrood is caused by a virus. It too is related to stress in the colony-so keeping healthy happy bees should be your major goal.

As a Master Beekeeper, I have seen Sacbrood-but never in my own colonies. Dead larvae appear watery – like a loosely filled water balloon. The head is often lifted towards the top of the cell – resembling a canoe shape.

There is no treatment or therapy for Sacbrood disease. Requeening the colony may help the hive recover.

Images of honey bees dead from disease and workers with poor brood pattern due to sickness.

Diseases of Adult Bees

Adult honey bees are not free from the pressures of disease. Several viruses and pathogens, like Nosema, affect how long bees live and their foraging efficiency. All are factors that contribute to unproductive colonies.

  • nosema
  • paralysis
  • viruses – like DWV


Caused by a protozoan (Nosema apis or Nosema ceranae), Nosema disease could be characterized as a pest – but I will include it here.

While this condition does not always have a single symptom, distended abdomens and dysentery (excessive bee poop) is often noticed. No true preventative measures are available but symptoms can be treated with Fumadil-B.


Two different viruses cause shaking symptoms in honey bees. Both the chronic bee paralysis virus (CBPV) and acute bee paralysis virus (ABPV) result in trembling bees that are often on the outer edges of hive frames. There is no cure for a virus.

Deformed Wing Virus

Adult bees with deformed, shriveled wings are suffering from a virus called Deformed Wing Virus (DWV).

This is very common in colonies that are suffering from hive levels of varroa mites. There is no cure for this virus – but controlling mite levels is important.

Bee Parasitic Mite Syndrome (BPMS)

BPMS is not a single disease but a complex group of symptoms resulting from varroa mite infestations and the viruses they spread.

Colony population dwindles down to low levels, bee pupae may be uncapped with their heads missing and sunken brood cells. This can be avoided by using varroa mite treatments (when needed) to keep colonies healthy.


What are the common signs of honey bee diseases in a colony?

Some of the most common disease symptoms in honey bees are: brood that is discolored or laid in an abnormal pattern and adult bees that act erratically: shaking, unable to fly etc.

How can beekeepers prevent the spread of diseases within their colonies?

Beekeepers can implement good hive management practices, including regular inspections, maintaining hygiene within the hive, and using disease-resistant bee stocks.

What is the most common honey bee disease?

American Foulbrood is one of the most common honey bee diseases and the most feared by beekeepers. It can be deadly for the colony.

A Final Word

As a beekeeper, reading about the many honey bee diseases out there can seem rather scary. However, many of them will never be found in your apiary. With proper hive management and care you can avoid some of the angst of sick bees. Still, you need to understand what they are and be ready to take action if needed.

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