螟蛉子

Etymology
See.

There was a long-held (but incorrect) belief by the Chinese that moth larvae are carried by wasps (thought to be unable to reproduce themselves) to their hives, kept there and raised as if they are the wasps' own offspring.

This has turned out to be a false impression, as the caterpillars are actually taken by the wasps as food for their larvae, but the metaphor of a moth larva or caterpillar for an adopted child has remained.

Noun

 * 1)  adopted son; adoptive children