Zecui

These chitinous entities can only grow to adulthood within a host creature, usually a humanoid or larger animal. When such hosts are particularly plentiful, zecuis can multiply at a horrifying rate, sealing hosts in subterranean chambers until their larvae grow to adulthood. However, during lean times, zecui adults will sate their hunger by eating those hosts along with any unlucky larvae gestating within, unable to be infested by their own young.

Between periods of wakefulness, zecuis hibernate for decades in burrows or buried within the soil. Sometimes an unincubated larva will be buried this way, waiting for a living host to come in contact with it. Once a zecui larva has gestated long enough to take control of its host, it may seek out larger and more powerful entities to devour the host, transferring themselves to a more plentiful source of food.