'aphid-killing' originates from English, specifically the compound of the words 'aphid' and 'killing' (present participle of 'kill').

'aphid' comes from New Latin 'Aphid-' ultimately from Greek 'aphis' meaning 'aphid'; 'kill' has Old English/Germanic roots (Old English 'cwellan' and related Germanic forms) and developed into modern English 'kill'; the compound 'aphid-killing' is a productive modern English formation combining the two.

Initially the elements meant 'aphid' (the insect) and 'killing' (act of causing death); as a compound it straightforwardly came to mean 'causing the death of aphids' and is used adjectivally to describe agents or actions effective against aphids.