A Geographe resident was shocked to find hundreds of honey bees had dropped dead in his backyard after they had been buzzing around a flowering gum tree.
Andrew Sexton said the bees had dropped in large numbers over the last week, when they hit the ground they would stumble around then die.
"This seems to have been going on for a whole week," he said.
Sheila Jacobs said once the bees dropped they could not fly or navigate, they would fall over and crawl on their side before flipping on their backs and dying.
"Something is wrong but I am not sure what," Mr Sexton said.
Busselton Bee Man Trevor Hooper is a registered apiarist in Busselton who relocates bees nesting in and around homes and buildings throughout the South West.
Mr Hooper said at this time of year there was a poor nectar flow and there would be one group of bees defending a tree if it was flowering.
He said the bees would be stopping other groups of bees from taking the nectar, and once the strongest hive had possession of a tree they would defend it vigorously by attacking the weaker group.
"The bees fight then drop to the ground and that is the end of them, would you believe they can actually do that," he said.
An Australian study, published in the American Naturalist Journal in 2014, found it was common for people to see big swarms of bees around trees and houses, which were fighting swarms.
The BBC reported in 2014 that the study's lead author Dr Paul Cunningham said if you stood under a swarm, you could see bees dropping out of the air.
The article stated the bees would grab hold of each other in a death grip and both bees would die. The fighting bees were female members of a colony that could not reproduce but collected pollen.
Australian Native Bee Research Centre Dr Anne Dollin reported on aussiebee.com.au other Australian research showed fighting swarms were caused by bees from one hive attacking or trying to enter another hive.
Dr Dollin stated fighting swarms were an effective way of defending a hive from invasion, however thousands of bees from both the attacking and defending hive might die in combat.
She said the swarms could last for many days, preventing working bees from carrying out their normal foraging.
The Department of Primary Industries and Regional Development stated the swarming process was part of the normal reproductive life cycle of honey bee colonies.
While more common during spring weather, an abundance of nectar and pollen provided ideal conditions for bee colonies to increase quickly.