Having imported ladybugs into a greenhouse for the express purpose of exterminating aphids, I can tell you with certainty that they’re kinda dumb. A leaf completely coated with aphids will see 4 plucked and obliterated by mandibles, and 50 ignored, only to search for more distant prey. The buffet is right there, why are you searching for scraps beneath it?
But there’s nothing quite like seeing the little shits disappear into an organic shredder, clawing desperately, fruitlessly at survival. I fucking despise aphids.