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A medium-size (2.8-3.3 cm wingspan) broad-winged moth with yellow-brown or dark tan forewings and white hindwings. The forewings are drawn out into a prominent curved hook at the apex, have a strongly toothed outer margin, and are crossed by two straight, fine dark brown lines. A small black point indicates the reniform spot. The hindwings are much paler than the forewings, are crossed by a faint median line, and have a narrow dark terminal line. The hooked forewing apex will identify this species as a hooktip, and the toothed forewing margin and pale almost unmarked hindwings will separate it from the other two hooktips, the Arched and Rose Hooktips.

The Two-lined Hooktip is nocturnal and comes to light. The long flight period may indicate at least a partial second brood. The larvae, known as the Warty Birch Caterpillar, is described and illustrated in Ives and Wong, 1988. It is reported to be a solitary defoliator (Prentice, 1963).