This one has me kind of stumped. While I haven't heard of beetles specifically eating cork, it doesn't surprise me in the least (some beetles are known to bore through lead casings).
The questions is, what kind is it?
I can't find anything on "cork weevil" (a weevil is a member of the beetle family Curculionidae)- one might exist, but I don't know about it.
It could be a "larder beetle", one of several species in the family Dermestidae. These beetles are known to eat everything from cured hams to carpet. I hadn't realized this, but some adults have been known to chew into cork. If there was an infestation in the basement...
There is a minute chance that it could be a Pachnoda marginata larva (from the beetle family Scarabaeidae). Some people raise these critters 1. to feed the larvae to pet lizards and 2. because the adults look cool. I believe they originated in Africa. Anyway, apparently the larvae bore right through cork.
Finally, there are entire families of beetles (thousands of species) dedicated to chewing though the bark of trees. I don't know of any that particularly go after cork, but there is a chance that the cork was infested before it was placed in the bottle. Luckily, the critter ate outwards instead of inwards.
I'll look into this a bit farther. Does anyone have the corpse? I'll be glad to take a look at it!
I never drank anything stronger than beer... before I was twelve.- W.C. Fields