How To Treat American Foulbrood [Best Practice]

Beekeeper checking for American foulbrood

American foulbrood may not be as prevalent as it was a century ago, but it still brings catastrophic results to hives.

If your hive is diagnosed with the disease, or you suspect it’s got it, you must act swiftly. An outbreak spreading through neighboring hives and commercial apiaries could have disastrous consequences. 

What to do if your hive has American foulbrood

If your bee colony is infected with American foulbrood, the most effective way to stop the spread is burning the hive. Any associated equipment and tools must also be burnt. All nearby hives should be treated with antibiotics and monitored closely for signs of contamination.

Beekeepers need to understand the regulations in their state or country. In many locations, the beekeeper must burn any infected hives on the evening of discovery. AFB is also a reportable disease in some areas, so check with your local apiary inspector to learn more.   

Why do I need to act fast?

Colonies inflicted with foulbrood quickly become weak, and hive numbers will drop. The weakened colony soon becomes vulnerable to robbing, allowing spores to be transmitted.

Bees may also drift to nearby hives. Eliminating the diseased hive as quickly as possible reduces the chance of an entire cluster of hives getting wiped out by American foulbrood.

What if local laws don’t require me to burn the hive?

In some areas, burning the colony isn’t a legal requirement, although you may still need to report it.

Even if there is no law enforcing a burnoff, best practice is to burn or irradiate. If the below conditions are met, using antibiotics combined with the shook method may be sufficient. 

  • no apiaries nearby
  • the colony is large
  • foraging season is early

If this applies to your situation, skip down the page to learn more about the shook method. Click here to jump down> 

Before you proceed: Are you sure the hive has American foulbrood? Pictures of sick-looking brood often pop up on beekeeping forums and social pages.

Some beekeepers conclude it’s AFB when it often isn’t. Learn the common symptoms of American foulbrood in this handy guide. 

5 American foulbrood treatments

1. Burning the hive

Euthanizing a hive is never easy for beekeepers, but it’s crucial to consider the big picture. Act fast to stop a small problem from turning into a big one.

American foulbrood is highly contagious and wreaks havoc on even the most robust colony.

A diseased beehive on fire to remove foulbrood
Burning the hive is a sure-safe way to kill off American foulbrood.

The most humane method involves killing the bees before burning. If possible, destroy the colony on the day of diagnosis. Always wait until evening to ensure all forager bees have returned home.

Steps to burn a hive

  1. After dusk, seal the entrance using tape, hive closer, or dirt.
  2. Use tape to seal any other cracks and holes that could allow an escape route for the bees.
  3. Smoke the bees if needed and then move the smoker to a safe place away from the hive.
  4. Quickly and quietly open the lid, pour one cup of gasoline (petrol) over the bees and frames, and then close it.
  5. Allow 10 minutes for the bees to die. Use a second cup of petrol if some bees are still alive.
  6. To stop any honey or wax from escaping during the burn, dig a hole at least 12″ (30cm) deep in the ground. Clear any dry grass or other combustible material next to the hole.
  7. Place the diseased hive, infected equipment, and gloves in the pit and burn, then cover with soil. 

Quick facts about burning a diseased beehive

  • Soapy water is a good substitute for gasoline if you need to kill bees.
  • Keep salvaged comb and equipment away from robbing bees.
  • Avoid inhaling smoke from old beehives painted with lead-based paint.
  • Wax is highly flammable so use caution when burning.
  • The hive boxes, covers, and bottom boards can cause a chimney effect.

Can I burn a beehive during a fire ban?

Beekeepers should never burn hives on fire ban days. They may also need to seek a fire permit, depending on the location.

Where fires aren’t permitted, it is best to double bag all equipment and take it to a commercial incinerator or landfill. Make sure the bags are durable and watch that honey doesn’t melt and run out of the bags.

Can I eat honey from a hive with AFB? 

Honey from foulbrood-infected hives is safe for consumption as the disease doesn’t affect humans. Extreme care is necessary during honey extraction to avoid transferring the bacteria. Wash down any equipment to remove spores after production.

Never feed honey from diseased hives to bees and always advise honey packers of its origin.

2. Irradiating the hive

Research has shown that 10 kilorays of gamma irradiation will successfully sterilize hives infected with American foulbrood.

Once the procedure is complete, honey bees will happily move back into the disease-free boxes and comb.    

Steps to irradiate hive equipment

  1. Depopulate the hive and extract any honey.
  2. Use a cloth to wipe off any insects and foreign matter.
  3. Strap materials together in lots of no more than 55 pounds (25kg).
  4. Shrink wrap or bag the equipment, then label and arrange for delivery to the nearest irradiation plant.

While irradiation is a highly effective way to remove AFB, exposing infected equipment to dry heat at 266˚F (130˚C) will also kill the spores.

3. Scorching beekeeping equipment

A propane torch can be used to sterilize boxes. It is a good option for beekeepers that don’t want to burn them and can’t access irradiation services.

It is difficult to guarantee the total removal of AFB using the scorching method. We suggest using another sterilization method in conjunction with this one.

To scorch boxes, slowly move the flame over each surface, browning all the wood. Be sure to get the fire into any hidden gaps and corners. Leftover propolis or wax should be heated until it melts into the wood.

Burning hive boxes to remove American foulbrood
Scorching hive equipment helps remove American foulbrood.

4. Wax dipping equipment

Dipping contaminated beekeeping equipment in hot wax will make sure nothing gets missed.

Wax heats deep into the wood, so it’s worth doing after scorching. The biggest challenge with this option is that a hot wax dipping vat is required.

  1. Contain the disease-ridden equipment in a location that bees can’t access until it is time to dip.
  2. Wear heavy-duty safety boots, gloves, mask, and a suitable shirt and pants.
  3. Fill the dipping tank with a 2:1 mix of paraffin wax and microcrystalline wax.
  4. Heat the wax to 320°F (160°C) and immerse the parts for at least 10 minutes. Check the temperature frequently to make sure it is hot enough.
  5. Carefully remove the materials and allow them to cool.

5. Antibiotics

It is best practice to treat surviving colonies with antibiotics after American foulbrood has been detected. This additional step will help prevent drifters from spreading the infection.

Antibiotics control the spread of American foulbrood but aren’t effective against spores. Using hard chemicals without removing diseased larvae will result in colony re-infection once the course of antibiotics ends.

Removing infected frames without a follow-up of antibiotics could allow adult bees to transfer the disease to a new colony. 

In the United States, antibiotics are only available through licensed veterinarians. Three products for dealing with AFB are available:

  • Tylosin Tartrate (Tylan)
  • Oxytetracycline Hydrochloride (Terramycin)
  • Lincomycin

We also recommend reading up on American foulbrood preventative measures.

What is a shook swarm?

If it isn’t a legal requirement to burn the bees, making a shook swarm may be possible.

This method is only suitable for large colonies that get infected early enough in the season to start their hive from scratch. If these conditions aren’t met, euthanize the bees.

A frame exchange involves shaking adult bees onto clean new equipment. Take extreme care to avoid re-infection.

  1. Use clean gloves and tools to set up a new hive for the bees to get transferred across to.
  2. Shake or brush bees from the old equipment into their new home.
  3. Dispose of old frames, dirty gloves, and other tools like brushes appropriately so no bees can access them.
  4. Apply a treatment of antibiotics and continue to monitor the colony for foulbrood symptoms.
  5. Feed the bees 1:1 sugar water until they build up food stores.

Summing up

Hives with American foulbrood will cause massive harm to surrounding colonies, so don’t leave it a few days before reacting.

In many cases, beekeepers will need to burn the hive. While this sounds like a traumatic task, it’s the best way to stop the disease in its tracks.

Those in areas that aren’t required to burn the colony may want to do so anyway. AFB is hard to eliminate, even when you’re meticulous with your cleanup procedure.

If you decide to make a shook swarm before disposing of the diseased hive, remember that antibiotics are still essential. Adult bees likely have spores of Paenibacillus bacteria that will activate once fed to larvae in the new hive.

New research in phagotherapy (aka phage therapy) is showing promising results in the treatment of American foulbrood. Source. However, more conclusive studies are needed before we can adopt this cure in the field.

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