I know that the Endless created the Cravers out of an "insectiod species" but the games haven't exactly been clear.


Because in the Endless universe you have 2 possible sources of the base material.


The Tikanan may not seem that likely, but they are collective insect species and have some similiarities. 


The Necrophages seem to be the most likely due to the interference of the Endless on Auriga and their distaste for the "new arrivals." 


So which base did the Endless chose, or did the Endless synthesize the Cravers out of both species adding a sizable dash of bio-cybernetics to boot. 


Maybe a unique reveal quest, if the Cravers colonize Auriga and they say "we found traces of creatures that look to similar to us in social and cultural hive organization."