The crash occurred on Tuesday when a van was transporting 72 beehive frames, each containing around 20,000 bees, reported French newspaper La Dépêche.
On a road in the southern town of Saussenac, the van smashed into a car, crushing most of the hives.
As the honey inside the frames was still in the liquid stage and yet to be processed by the bees, the vast majority of the colonies became stuck in their own supply of nectar.
Beekeeper Dominique Miras told the paper that the bees were "glued into a kind of puree".
Several thousands of the insects are believed to have flown to safety, and hives have been set up by the roadside in an attempt to lure them back.
But with an estimated 1 million or more believed to have died, the damage is already done.
Miras reckoned he was at a loss of around €7,000 due to broken equipment, not to mention the damage to the van and the serious hit to his profits from the irretrievable honey harvest.
With the rescue teams forced to work through swarms of agitated bees, both drivers were able to escape with only minor injuries.
(The honey supply was still at liquid stage. Photo: David Illig/Flickr)