Bumblebee sex?

Do bumblebees mate on the wing, or are they cannibalistic?
I just saw one fly by carrying another.
Has he swept her off her feet? Or has she turned him into meat?

Curious minds want to know....

Well, mating methods depend on the bumblebee species, but none of them shows cannibalistic behaviour.

Usually male bumblebees only live a few weeks anyway, and as far as I could see there are three main mating techniques:
1) hilltopping: drones gather at elevated spots and wait for queens (which only mate once)
2) cruising certain paths, leaving pheromones. A quite interesting behaviour already described by Charles Darwin. The drones fly along certain paths that are followed by the next drone generation through some not fully researched "inherited tradition"
3) hovering around the exit of a bumblebee nest where the new queen is about to emerge (similar to many solitary bees).

Thanks for the question, I have never researched bumblebee mating before ! :-)