American Foulbrood Disease

American Foulbrood (AFB) is a serious disease that affects honeybees caused by the spore-forming bacterium Paenibacillus larvae.  California law states that no person shall maintain, spread or conceal AFB within an apiary. Beekeepers should conduct routine inspections to observe signs for AFB infestation.Ropiness test on honeycomb infected with American Foulbrood Disease

Common signs and symptoms

American Foulbrood can be identified by the following characteristics:

  • Irregular capped brood pattern
  • Gummy larval cell that “ropes” out upon insertion of a toothpick
  • Foul unpleasant odor
  • Hard black scale that is difficult to remove with a pupal tongue

The United States Department of Agriculture (USDA) Bee Research Laboratory provides more detailed information on how to identify American Foulbrood Disease.

Preventing the spread of AFB

Beekeepers should minimize cross contamination of spores among their hives by sanitizing hive tools between inspections.  AFB spores may remain viable for many years in old equipment.  As required by California law, you must ensure that your shipment has been inspected and certified as free from American Foulbrood prior to ordering new bees.

Furthermore, California law prohibits:

  • Selling diseased bees, comb, hives, appliances or colonies
  • Abandoning a diseased apiary
  • Exposing other bees to comb or honey
  • Extracting honey, pollen or wax except in a building or an enclosure that restricts access by bees
  • Open-air feeding
  • Possessing comb not occupied by a live bee colony, unless tightly secured to prevent access by bees

AFB testing and abatement

Please contact our office if you suspect AFB in your apiary. Detection of AFB requires immediate eradication to contain further spread of the disease. Prior to abating infected hives, an official sample may be collected and sent to the USDA Bee Research Laboratory in Beltsville, MD. Our biologists can provide authorization on the Bay Area Air Quality District burn notification form (PDF) for legal abatement. Infected hives must be burned and the ashes should be buried at least two feet deep. If burning cannot be done safely at your location, please contact our office for alternative disposal measures.


Bay Area Air Quality District burn notification form (PDF)

Contra Costa County Fire Protection District burn permit (PDF)


Bee Informed Blog

Bees in the Neighborhood: Best Practices for Urban Beekeepers (PDF)

USDA Bee Research Laboratory