大の虫を生かして小の虫を殺せ

大(だい)の虫(むし)を生(い)かして小(しょう)の虫(むし)を殺(ころ)せ

expressions (phrases, clauses, etc.)proverb

sacrifice something small in order to save something great; lose a leg to save one's life; let a large bug live and kill a small one