Difficult to diagnose. A small group of worker bees and a queen settle outside the colony entrance on the side of a box or below the bottom board. Worker bees then enter colony to kill the existing colony queen. The remainder of the swarm move into the colony and the queen of the invading bees becomes the egg layer. Colony temperament may change following usurpation.
Nest usurpation is a form of reproductive parasitism that may contribute to the ability of Africanized bees to displace European (i.e., western) honey bees in the Americas. In usurpation, a group of bees (sometimes termed a swarm) with a queen settles on the outside of an established colony close to the entrance. Worker bees from this group enter the hive and kill the existing colony’s queen, and then the remaining bees move into the hive, all within 15 minutes from start to finish, to take over the existing colony. Some fighting between workers of the two groups may occur. Original queens may not be immediately killed. When they are, it is presumably done via worker-balling behavior. Dead queen bodies are discarded outside the hive. Usurpation behavior is not widely known to occur in European bees.
swarming, robbing, balling queen
Mangum W. 2018. Usurpation: A Colony Taken Over by a Foreign Swarm. American Bee Journal 159(5): 537-541. https://bluetoad.com/publication/?i=580808&p=57&view=issueViewer and https://bluetoad.com/publication/?m=5417&i=580808&view=articleBrowser&article_id=3356173&ver=html5
Mangum W. 2013. Colony Takeovers (Usurpations) by Summer Swarms: They Chose Poorly. American Bee Journal 153(1): 73-75. https://bluetoad.com/publication/?i=138095&p=73&view=issueViewer and https://www.bluetoad.com/publication/?i=138095&article_id=1256280&view=articleBrowser
“Usurpation – When Bees Take Over Another Colony”. YouTube, uploaded by Bee Life, 21 April 2019. https://www.youtube.com/watch?v=_SjSglgl65o
