73. What are common bee diseases?

When you begin beekeeping, one of the most important skills you develop is simply learning to notice when something isn’t right. Healthy colonies are active, organised, and steadily growing. But like all living creatures, bees can suffer from diseases.

The good news is that most common bee diseases are recognisable and manageable, especially when caught early.

Let’s look at a few of the most common ones you may encounter.

American Foulbrood (AFB)

American Foulbrood, often called AFB, is one of the most serious bacterial diseases affecting honeybee brood (developing bees).

It is caused by a bacterium that produces long-lasting spores. These spores can survive for many years, making the disease difficult to eliminate once established.

Signs to look for:

• Sunken, dark, or perforated brood caps

• A patchy brood pattern

• A sticky, rope-like larva when tested with a matchstick

AFB is highly contagious. In many regions, it must be reported to authorities, and infected equipment often needs to be destroyed.

European Foulbrood (EFB)

European Foulbrood (EFB) is another bacterial disease, but generally less severe than AFB.

It often appears when colonies are stressed, such as during poor weather or limited food supply.

Signs to look for:

• Larvae that look twisted or melted

• Yellowish or brownish colouring

• An uneven brood pattern

Unlike AFB, EFB can sometimes clear up on its own if the colony becomes strong again. Good nutrition and strong queen performance can make a big difference.

Chalkbrood

Chalkbrood is a fungal disease that affects bee larvae.

It is usually linked to cool, damp conditions and weak colonies.

Signs to look for:

• White or grey “mummies” (dried larvae) in cells

• Hard, chalk-like bodies that may turn black over time

• Debris at the hive entrance

Chalkbrood is not usually fatal to a colony, but it is a sign that something is not quite right. Improving ventilation, sunlight, and colony strength often helps.

Nosema

Nosema is a microscopic parasite that affects adult bees, particularly their digestive system.

It is more common in cooler months or when bees are confined for long periods.

Signs to look for:

• Bees that appear weak or unable to fly

• Brown streaks (dysentery) near the hive entrance

• Reduced colony strength over time

Nosema can be subtle and is often confirmed through testing, but good hive hygiene and strong colonies help reduce its impact.

Deformed Wing Virus (DWV)

Deformed Wing Virus is closely linked to Varroa mites.

The mites spread the virus, which affects developing bees.

Signs to look for:

• Bees with shrivelled or crumpled wings

• Bees crawling near the hive instead of flying

• A gradual weakening of the colony

Controlling Varroa mites is the most effective way to prevent this disease.

Keeping your bees healthy

While this list may seem a little overwhelming at first, there is a simple way to think about it.

Most bee diseases take hold when colonies are stressed or weakened.

Here are a few practical steps to reduce risk:

• Inspect your hive regularly

  
  

  Early detection makes a big difference.

• Maintain strong colonies

  
  

  A healthy queen and good nutrition are your best defence.

• Ensure good airflow and dry conditions

  
  

  Especially important for preventing fungal diseases.

• Manage Varroa mites carefully

  
  

  This helps prevent virus-related problems.

A calm approach

Every beekeeper encounters challenges at some point. Seeing something unusual in your hive does not mean you have failed—it simply means you are learning.

With regular observation and a steady approach, you will soon become familiar with what is normal and what needs attention.

Over time, this quiet awareness becomes one of the most rewarding parts of beekeeping—caring for a healthy, thriving colony.