A short clip from the BBC program “Ant Attack”
Driver ant males are astoundingly strange creatures. They are larger, more muscular, more exaggerated than most other male ants. The reason is likely linked to the behavior shown in the above video: males must first be accepted by a gauntlet of choosy workers.
A classic paper by Franks and Hoelldobler (1987) describes the theory. This preference of workers for bulkier males- and a corresponding slaughter of smaller or otherwise unsuitable ones- drives an evolutionary trajectory towards increasing monstrosity. It’s an ant version of the peacock’s tail.
Myrmecos Blog 
Wow. I watched the full show just yesterday! It was sort of slow though; I didn’t think it was actually exciting until when they started invading the termite nest.
I nearly laughed when I saw how bulky the male was, really. Looked like if you took a male ant and infused its genes somehow with some scarab genes. It almost looks like it can’t fly.
Hi Alex,
the “sexual selection” scenario proposed by Franks & Hölldobler is plausible but there is also another, simpler explanation. Daniel Kronauer and Koos Boomsma suggested that males need to have a similar size as queens in order to be able to mate. Otherwise they would not be able to hold the queen during the copulation. Check out the paper
http://www.springerlink.com/content/y24185726x4u2770/
Cheers,
Caspar
Thanks Caspar- I hadn’t seen that paper.