Workers in an urban bee hive were killed in a swarm of hornets last week, the first recorded honey bee colony collapse.
The honey bee deaths came as a surprise to beekeepers in London and elsewhere in the US, but researchers say they are likely to be the first documented cases of hornet deaths in Britain.
The bees were killed on 22 April in a hive at the University of Leicester, according to the London Beekeepers Association.
The beekeepers said the swarm, consisting of at least 10 honey bee colonies, was about 1.5 metres (6ft) in diameter, and consisted of a total of 100 hornets, a few smaller ones and a few larger ones.
Hornets can be deadly because they are able to feed on the sap from plant and tree roots.
Insects are the main predators of the bees.
“The hornets were attacking and damaging the hive, and we had to stop the bees from moving,” said Chris Wood, beekeeper at the university’s agricultural research laboratory.
“The swarm is probably the most dangerous one we have seen yet.
Hornet damage has increased over the last two years, with the number of hornett attacks in recent months increasing by around 60 per cent.”
The hive was closed for about a week to remove any insects and to ensure the bees were protected from any future attacks.
Wood said the beekeepers were told they could be fined for failing to ensure there was no further damage to the hive.
He said the hive was safe and sound.
Researchers say the hornet swarm had been increasing in size in recent years and that it was likely to continue rising.
In December, honey bee numbers in England were estimated at about 1,000,000 in England and Wales, and were expected to hit the 10 million mark by 2019.