This is an immature life stage of an insect. But some people also use the term to describe the early life stages of fish, frogs or other animals. Usually, the larva looks very different from the adult it will become. A caterpillar, for example, doesn’t look much like a butterfly. The larval stage of the insect may also have completely different organs and structures than the adult, as well as a different diet. A frog larva has gills and breathes water, while the adult frog will come to the surface to fill its lungs with air.
Larvae (the plural of larva) are often adapted to very different environments than they will live in as adults. Adult mosquitoes are airborne, for instance. But their larvae hang out in small pockets of still water. There they gobble up algae and bacteria living on the water’s surface.
In a sentence
The larva of a cattle eyeworm infects the stomach of a fly, but guess where it goes after it grows up.