FGM044b: The Ecology of the Carnivorous Caterpillar
 
This is pretty much a throw-away "monster" for an OSR campaign, but like many things of this nature, it all really depends on what a GM decides to do with it.

This Ecology download is just to fill in some small corner of the game world with flavor and is a companion piece to my Tweak & Toss adventure seed The Eaters of the Dead (FGM044a).