Bundaberg beekeeper Kai Gerschau thought his native bees were mating when he first spotted the massive black swarm in his backyard, but a closer look revealed it was not love at all — it was war.

Key points: A Queensland beekeeper noticed an "unusual" black swarm of bees in his backyard which, at first sight, he thought was a mating swarm

A Queensland beekeeper noticed an "unusual" black swarm of bees in his backyard which, at first sight, he thought was a mating swarm A closer look revealed hundreds of dead bees, indicating that they were in fact fighting for dominance over the hive

A closer look revealed hundreds of dead bees, indicating that they were in fact fighting for dominance over the hive The species pose no threat to humans and the hive will continue to thrive once the new queen installed

"I came out and the swarm was massive, there was a lot of energy in the air, it was unusual," he said.

"We often get swarms but normally they are mating swarms and they look a bit different."

But a closer look at the hives revealed the true carnage.

"I discovered all these dead bees and I realised for the first time I had a fighting swarm," he said.

The swarm lasted more than 24 hours, as an invading colony of bees attempted to set up a new home in one of Mr Gerschau's existing hives.

"They will fight and fight until they can get in, they will find the queen, they will kill the queen and they will put a new queen in and from that moment onwards they own the hive," he said.

The queen is dead, long live the queen

The native stingless bees are often kept in backyards as garden pollinators and produce about one kilogram of honey each year.

Mr Gerschau said it was impossible to know if his bees won or lost the fight, but activity would go on at the hive regardless.

"For the beekeeper it does not really make a difference who wins or loses, it just looks very sad if you see all the dead bees in front of your hive," he said.

The native bees are stingless, and pose no danger to humans while they are swarming, and Mr Gerschau said they have been a valuable addition to his family garden.

"They don't do any damage [to us] … I love them, the kids love them, what's not to love about them?" he said.

"Before you know it, you get very passionate about your little fluffy bees."

It is not uncommon for native bees to fight over a hive. ( Supplied: Kai Gerschau )

Entomologist Tim Heard has researched and written about native bees for 35 years, and said the fighting swarms are a natural, if somewhat brutal, behaviour.

"A single hive comes under attack and you see a lot of bees swarming around the entrance," Dr Heard said.

"They bite on to each other with their jaws and fall to the ground and they die like that — that's the end for both bees and that happens in the thousands.

"We have counted 20,000 dead bees underneath one fighting swarm.

"The defending bees don't take it lying down, they fight back and the end result may be that they successfully back the attacking bees or they may be overtaken."

Whole hives fall to the game of drones

Dr Heard said the takeover would eventually change the entire genetics and even the internal structure of the hive.

Loading

While bees become more active in the warmer weather, he said the behaviour was thought to be a natural expression of aggression, particularly in the social species Tetragonula hockingsi.

"They're a bit like honey bees in the sense that they've got highly sophisticated colonies, a queen and many workers and they live perennially for many years and they store food for the future, particularly honey," he said.

"It's just part of the life of these bees, they've evolved this aggressive behaviour at some point in their past and they continue to do it, the do it in nature and they do it in artificial situations.

"We don't believe it's the result of keeping them at high density, for example, that causes this fighting behaviour, we think it is natural behaviour they're just expressing what they do in the wild."

While potentially confronting for some, Dr Heard said the bees were harmless and the swarms posed no risk to the public.

"These bees attract a lot of interest by people and people keep them, they are fascinating and they're very attractive and they're very interesting and they're useful too," he said.

"People keep them in hives but they also occur in cavities so they do colonise spaces and there may be one of these swarms appear."

When the bees attack each other, both die in the exchange. ( Supplied: Kai Gerschau )

But Dr Heard said they were often confused for flies or pest insects, and well-meaning people might be tempted to spray them.

"We should be aware of what they are and we should leave them alone because they are good for the environment and for us as humans," he said.

"We definitely should protect them, they don't do any harm and certainly I would encourage people to learn to love them."

It was a sentiment Kai Gerschau shared.

"Often they're in water meters, things like that," he said.

"Don't kill them, let somebody know they'll happily come and remove them."