堤潰蟻孔（隄潰蟻孔）　

◎ 堤潰蟻孔 dīkuì-yǐkǒng

[a dam (or dyke) bursts because of ant‘s cares] 堤壩因螞蟻洞而崩潰。比喻忽視小處會(huì)釀成大禍

臣聞輕者重之端,小者大之源,故堤潰蟻孔?！獫h· 陳寵《清盜源疏》