Largest of the giant beetles, between 10 and 14 feet long with brown or grey carapaces and huge horns
Giant rhinoceros beetles are the largest of the giant beetles, being between 10 and 14 feet long. They have brown or grey carapaces and huge horns, from which they get their name. They attack with their horn or by trampling opponents (but cannot apply both attacks to one opponent in the same round, nor can they trample large-sized creatures). They are territorial and thus prone to attack any interlopers.
Basic Fantasy Field Guide Omnibus
Massive tropical beetle that feeds on fruit and vegetation
Usually encountered in the tropics, these massive creatures (roughly 12-ft long, plus another 6-ft of horn) live on the fruit and vegetation they crush as they roam about.
OSRIC