Thread:MemeDaddy1233/@comment-32329805-20180604021557/@comment-32329805-20180604025440

Directly from the Calamity Wiki:

For all of their potential for growth and killing power, worms have been looked down upon by their enemies and regarded as little more than burrowing pests for centuries. However, the rise of the Devourer of Gods turned such a conception completely on its head, instilling a fresh wave of fear and paranoia into the world at large. Worms were no longer merely exterminated for being a nuisance, but actively hunted and wiped out. The Devourer's own species - already regarded with caution for their power to assimilate the abilities of their prey - was rendered virtually extinct within the span of a few short years.

It was only by the hand of fortune that the Devourer itself happened across the last of its species: a newborn worm that could hardly fend for itself, starving and on the brink of death. The Devourer took pity on its fellow kind and brought it to Yharim's forces, who restored it to health and outfitted it with armor akin to that of the Devourer. Despite having spared it once, the Devourer of Gods is highly aware of its protégé's potential, and would not hesitate to turn against the lesser worm should it grow strong enough to threaten its master.

However, that day has not yet come. The newly christened Storm Weaver resides in the outer reaches of the atmosphere, preying on the wyverns that roam the skies with it. Though lacking the advanced mind developed from assimilating countless human prey, it has enough capacity to process the orders given to it - while retaining the feral animosity of a beast to direct against those it hunts.