Glossary
Any pathological condition affecting honey bee brood (eggs, larvae, and pupae). Major brood diseases include American foulbrood (AFB), European foulbrood (EFB), chalkbrood, sacbrood, and stonebrood. Early detection and proper management are essential for colony survival.
American foulbrood (AFB) is the most serious brood disease, caused by the bacterium Paenibacillus larvae. AFB forms highly resistant spores that can remain viable for decades in contaminated equipment. Infected larvae turn brown, develop a ropy consistency (the 'matchstick test'), and produce a distinctive foul odor. Most states require that AFB-infected equipment be burned.
European foulbrood (EFB) is caused by Melissococcus plutonius and is less devastating than AFB. EFB typically strikes in spring when colonies are building up rapidly and nurse bees cannot keep pace with feeding demands. Unlike AFB, EFB can sometimes be resolved by requeening with a hygienic queen and ensuring adequate nutrition.
The best defense against brood disease is regular inspection. Beekeepers should examine brood frames for irregular patterns (scattered capped and uncapped cells rather than solid, consistent coverage), discolored or sunken cappings, larvae in unusual positions, and any abnormal smell.
Good apiary hygiene practices significantly reduce disease risk: never share equipment between hives without sterilization, replace old comb on a regular rotation cycle, maintain strong colonies with adequate nutrition, and use hygienic bee stock that actively removes diseased larvae.
The field test is the matchstick or toothpick test: insert a small stick into a suspect cell, twist, and slowly pull out. If the contents stretch into a ropy string of 1 to 2 inches before breaking, AFB is strongly suspected. Laboratory confirmation through your state apiary inspector is recommended.
AFB has no cure; infected hives and equipment must typically be destroyed to prevent spread. EFB can sometimes be resolved through requeening and nutrition management. Chalkbrood and sacbrood are usually self-limiting conditions that resolve with improved ventilation, nutrition, and requeening.
Antibiotics (oxytetracycline) were historically used for EFB and as a preventative for AFB, but their use is now regulated and requires a veterinary prescription in the United States. Antibiotics cannot kill AFB spores and may mask symptoms, allowing the disease to progress undetected.
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