Parasites are generally favored, since they hatch on the eggs of their enemies and then consume them until there is no more to be eaten.
它們大多數都很「專情」，只產卵寄生在同一種蟲的卵、蛹或成蟲身上，直到害蟲身上養分被吃光死亡為止。少數捕食性昆蟲也有偏愛，例如食枒蠅只吃丫蟲，澳洲瓢蟲只吃介殼蟲。