I don't know about wood worms. Do you have wood worm infestations wherever you live? How old is this ukulele? If it is some sort of wood eating worm, why did it pick that particular place to burrow in? Has it been sitting out, or has it been in a case? How far down does the hole go if you stick a toothpick or something down in it? If it is a worm, is the worm still in there? If you stick a toothpick down in there, does it come out with worm guts on it? I would be more inclined to believe that it was there when you got it, but I'm just guessing. I mean, that's all I can do, is guess.