I mean these are horrible things, the meat eating maggots in rotting corpses. Of course there should be giant ones, and their means of attack and feeding should be equally unpleasant.
Giant Bluebottle
by Cab Davidson
Stat Bluebottle, Giant AC: 4 HD: 3+2 Movement: 150' (50') Attacks: 1 vomit Damage: 2d6 No. Appearing: 2d8 (2d8 or special) Save As: F2 Morale: 7 Treasure Type: U Intelligence: 0 Alignment: Neutral XP Value: 50 Resembling a 3’ long giant housefly with detail of its otherwise jet black form picked out with blue iridescence, the giant bluebottle is by preference a carrion eater, but when desperate or threatened it will attack living foes. Its means of attack is horrific – it literally vomits highly corrosive digestive juices on a foe. They are, thankfully, rarely keen to attack. They can be found underground or in the wilderness, and where a huge carcass is rotting they can swarm in massive numbers, with tens or even hundreds able to breed from the site of a rotting dragon, for example.