In early May one of the colonies in my teaching apiary started to display excessive defensive behaviour, following and stinging people for about 100 metres from the hive. I practice a zero-tolerance policy for this kind of behaviour for the following reasons:
- It is very unpleasant for me and for the people who come to the apiary to learn.
- It is bad for relations with the neighbours and members of the public passing by.
- The drones carrying the aggressive gene will mate with young queens from the area and pass on the bad behaviour to other beekeepers’ colonies.
The genetic line from which this colony was raised has so far been faultless. The colonies in my home and teaching apiaries are well known for their gentleness and calmness on the comb.
The queen was bred by me last year and until recently was being considered as an egg donor for queen raising this year.
Apart from genetic reasons, colonies can turn aggressive when there is a sudden end of a nectar flow, when robbing is taking place, when they are invaded by pests, when disturbed by noise or clumsy handling by the beekeeper. None of these conditions were present.
Varroa testing by CO2 produced only one mite from a sample of 300 bees. There were no signs of adult or brood diseases.
Recently, the Kakugo virus (KV), which was only detected in the brain of aggressive workers of Italian bees by real-time PCR, was suggested to trigger behavioural changes in honey bees1. My bees are not Italians, but there has been so much hybridisation that it’s impossible to know if there is any trace of Italian stock in their lineage. It’s a long shot, but it could explain the mystery of why a well-behaved colony turned nasty for no apparent reason.
Actions
The actions I took, with the help of leaners in the group, were as follows:
6 May – Couldn’t find the queen. Destroyed all the capped drone cells. Split the colony in two with the brood and young bees in a new separate brood box. United the new brood box with a calm colony by the newspaper method.
11 May – Uniting complete, combined colony calm and gentle.
11 May – Found the queen in the parent colony and killed her. We did this by moving the brood box a few metres to one side to bleed off all the flying bees then divided the brood frames into twos. Destroyed all the capped drone cells.
18 May – Destroyed all the queen cells.
19 May – Now hopelessly queenless, the remaining colony was united with a different colony by the newspaper method.
26 May – Uniting complete, colony calm and gentle.
Conclusion
Both colonies are calm and strong in numbers, building up for the summer flow.
It was possible to deal with an aggressive colony by:
- splitting up the flying bees from the nurse bees
- killing the drone brood to prevent the aggressive genes from being passed on during mating,
- culling the queen.
- uniting them separately with other colonies.
Reference:
1. Rortais A, Tentcheva D, Papachristoforou A, Gauthier L, Arnold G, Colin ME & Bergoin M (2006) Deformed wing virus is not related to honey bees’ aggressiveness. Virology Journal 3: 61
Alan Baxter
10 June 2025
Leave a comment