What are beetle larvae called?

'Water tigers' is a name that's given to the larval stage of the diving beetle [Dysticidae family]. The name comes from the larvae's relentless pursuit of food sources. Like the adult stage, the larvae know how to hide amongst and flit through pond and stream vegetation. They're the terror of many small pond animals, of which particular favorites are glassworms [Chaoborus spp] and tadpoles.