'larvae-harmful' is a compound word formed from 'larvae' and 'harmful'. 'Larvae' originates from Latin 'larva', meaning 'ghost' or 'mask', referring to the immature form of insects. 'Harmful' comes from Old English 'hearm', meaning 'injury' or 'damage'.

'Larvae' was adopted into English from Latin, while 'harmful' evolved from Old English 'hearmful'. The combination into 'larvae-harmful' is a modern English construct.

The term 'larvae-harmful' has consistently meant causing damage to larvae since its inception.