Actually, this is a nice way of saying it. The more correct way would be to say "hostile take-over". This usually occurs during dearth periods. A common trait in Africanized bees is to continue rearing young until they have used up all their food then search for a hive with resources to take over. Many times this is not Africanized taking over an European hive but a more aggressive colony overtaking a weaker one. Sometimes even a strong healthy one....what do the bees have to loose!
The photo below shows an Africanized Usurpation Swarm taking over a small Africanized colony that I removed a few months prior. The established colony was recovering from the removal and being fed supplements of sugar syrup and protein patty. The starving group of bees decided to take over what they had. We were out in the bee-yard working with this happened. We searched for the queen in the group of bees hanging on the outside of the box and didn't find her. We opened the established colony and found two queens on separate frames, both being balled. Since the Africanized queens were unmarked and not knowing who would win the battle out of the worker bees, we caged both queens. The queen whose workers won fed their queen while the other queen was ignored, and starved in her cage.
IF the hive being taken over was European, the marked queen would have been grabbed and put in a cage, the intruder queen killed. At this point since so many of the intruder worker bees had entered there was no separating the bees back. The European queen would need to stay in the cage as if she was being introduced to the colony. So always remember to keep your European queens marked.