§ Of the Flight of the Noldor The Silmarillion

But Ungoliant had grown great, and he less by the power that had gone out of him; and she rose against him, and her cloud closed about him, and she enmeshed him in a web of clinging thongs to strangle him. Then Morgoth sent forth a terrible cry, that echoed in the mountains. Therefore that region was called Lammoth; for the echoes of his voice dwelt there ever after, so that any who cried aloud in that land awoke them, and all the waste between the hills and the sea was filled with a clamour as of voices in anguish. The cry of Morgoth in that hour was the greatest and most dreadful that was ever heard in the northern world; the mountains shook, and the earth trembled, and rocks were riven asunder. Deep in forgotten places that cry was heard. Far beneath the ruined halls of Angband, in vaults to which the Valar in the haste of their assault had not descended, Balrogs lurked still, awaiting ever the return of their Lord; and now swiftly they arose, and passing over Hithlum they came to Lammoth as a tempest of fire. With their whips of flame they smote asunder the webs of Ungoliant, and she quailed, and turned to flight, belching black vapours to cover her; and fleeing from the north she went down into Beleriand, and dwelt beneath Ered Gorgoroth, in that dark valley that was after called Nan Dungortheb, the Valley of Dreadful Death, because of the horror that she bred there. For other foul creatures of spider form had dwelt there since the days of the delving of Angband, and she mated with them, and devoured them; and even after Ungoliant herself departed, and went whither she would into the forgotten south of the world, her offspring abode there and wove their hideous webs. Of the fate of Ungoliant no tale tells. Yet some have said that she ended long ago, when in her uttermost famine she devoured herself at last.