Key points
- Dysentery is a symptom, not a disease in itself.
- Common causes: long confinement, indigestible stores (honeydew), fermented syrup, nosema.
- Brown stains on combs, floor and hive front.
- Prevention: good-quality winter stores and a healthy, dry hive.
In winter, bees hold their faeces until a cleansing flight on a mild day. When the gut gets too full or the bees are sick, they relieve themselves inside the hive or just outside: this is dysentery.
Signs
- Brown or yellow stains on the hive front, landing board and roof.
- Soiled combs and crown board inside.
- An unpleasant smell when the hive is opened.
- A weakened colony at the end of winter.
Possible causes
Long confinement. A long, cold winter with no day mild enough for a cleansing flight.
Indigestible stores. Honeydew and some mineral-rich honeys leave more residue. Fermented or badly made syrup causes the same problem.
Nosema. Nosema apis is associated with late-winter dysentery1. A microscope test can confirm it.
Disturbance. A hive opened or knocked in midwinter eats more and gets restless.
What to do
- Let the colony make cleansing flights on the first mild days.
- Replace heavily soiled combs in spring and clean the floor.
- Have a bee sample tested if dysentery is severe or affects several colonies.
Prevention
- Winter on good-quality stores: avoid leaving honeydew in the brood box for winter where possible.
- Make syrup properly and never feed fermented syrup.
- Choose a dry, sunny site and do not open hives in cold weather2.
References
- Fries I. (2010). Nosema ceranae in European honey bees (Apis mellifera). Journal of Invertebrate Pathology 103: S73-S79.
- FAO, IZSLT, Apimondia, CAAS (2021). Good beekeeping practices for sustainable apiculture. FAO Animal Production and Health Guidelines No. 25.