A swarm is actually a reproductive process. It looks like a mass of bees, but it has a specific purpose and composition.

(Although maybe you’re right colloquially)

https://en.m.wikipedia.org/wiki/Swarming_(honey_bee)

A load of bees engaged in robbing behaves entirely differently from a swarm, which is a magical thing to interact with.

I'm just repeating what I found on the intarwebs: https://englishgrammarhere.com/collective-nouns/collective-n...