'larvae-reducing' is a compound formed from 'larvae' and 'reducing'. 'larvae' originates from Latin, specifically the word 'larva', where 'larva' meant 'ghost' (later adapted in zoology to mean an immature insect stage). 'reduce' (in 'reducing') originates from Latin, specifically the word 'reducere', where 're-' meant 'back' or 'again' and 'ducere' meant 'to lead'.

'larva' entered scientific English from Latin via Neo-Latin usage in natural history and came to denote the immature form of certain animals; 'reduce' passed into English from Old French and Latin ('reducere') and developed the sense 'make smaller' or 'bring back'—the compound 'larvae-reducing' is a modern descriptive formation combining these elements.

Initially, 'larva' referred to a 'ghost' or mask in Latin; over time it evolved into a biological sense referring to an immature animal stage. 'Reduce' originally meant 'lead back' but evolved to mean 'make smaller' or 'decrease'; 'larvae-reducing' therefore now means 'decreasing the number of larvae'.