Wiki suggests bumble bees only range a few kilometers. Is it even normal to see that many colonies that close together?
Probably the tree and surrounding vegetation were flowering abundantly, attracting many insects from the area. I would say thousands of insects on a large tree is not unfeasible at all, perhaps even tens of thousands. Whether they were all bees, and whether the bees were really all bumble bees, is not clear.
You're right that 25,000 bumble bees in one place does sound logistically difficult to arrange. We can back-of-the-envelope it...
(edit: increased foraging distance with data from reference, which slightly changes the conclusion)
It would be ~150 colonies within a several kilometer radius. If we assume mean foraging distance of 10km [1], thats (a rather beautiful) 314km^2 of source area. We should probably also assume that the vast majority of bees in the area are not visiting those two trees, as there are likely other good sources in the area too. If we assume 1-5% of the local bees might be visiting the trees, there would have to be a colony density of ~10-50 colonies per km^2. That is high, but not impossible. Previous measurements of bumble bee colony density have estimated in the region of 0.5 to 20 per km^2 [1].
So, one of the following is probable: the number of bumble bees is exaggerated in the story, or they weren't all bumble bees, or some of my estimates are wrong. I would arrogantly assert the first two are more likely :)
1. https://ir.library.oregonstate.edu/xmlui/handle/1957/35082
The reason I ask is the 1-5% figure you mention. I assume bees must have some mechanism to prevent sending bees to fatal sites. For ants, no one comes back, so no one keeps going. Ant traps short-circuit this by providing food with a slow-acting poison - the ants make it back with "food," causing more ants to be sent, and soon a significant portion of the stockpile is poison, drastically reducing numbers in the colony. Could that have happened here? It sounds like that's probably not the case, given that the bees appear to have died practically on contact with the linden trees.
But I don't know how bee flow control works.
Which is what they do routinely. Bumblebees have been known to fly up to 8 miles (13 kilometers) from their nest. http://news.softpedia.com/news/Scientists-Map-the-Flight-of-...
> a creature that has to violate physics to fly
Also, I wasn't under the impression that he thought bumble-bees can’t fly, but that he is of the belief that at one point in time, scientists couldn't explain how it’s physically possible and that that is where this factoid came from.
At 30 - 50km/h? Yeah, "Only".
The hypothetical human in your example would have a car that traveled a couple thousand km/h. Given which, we'd be right to say "only" of his 133km commute as well.