Whenever a giant spider assault seems too carefully orchestrated, or the PCs fall prey to a deadfall in the deep woods, it’s a safe bet an ettercap is involved.
A mated pair of ettercaps is about to have their first brood. With a full complement of giant spider pets, they lack only warm meat to feed their young, and have spent the week rigging extra spear traps and nooses to snag the unwary.
Not all ettercaps are devoted to spiders. Certain advanced ettercaps in the East have been reported to be comparatively gentle shadowsilk-spinners who tend their beloved gloomwings. Of course, the gloomwings’ tenebrous worm offspring are not gentle at all…and they are always exceedingly hungry.
Despite their low Intelligence, ettercaps have the woodcraft and the Wisdom to become druids. Some are blight druids (Advanced Player’s Guide 98–99); all have giant spider companions (Ultimate Magic 36–37). A rare gifted few are web savants, a variant of the menhir savant class that detects the magic of the ley lines via spider webs rather than standing stones.
—Pathfinder Bestiary 129
Dragon 343 has “The Ecology of the Ettercap” by Paul Leach and Russel, diving deeper into ettercap origins and society, and serving up more traps and nasty variants that could easily be adapted from 3.5 to Pathfinder.
By the way, this was another post that sat languishing with this placeholder for too long: