Lepidoptera and Trichoptera (caddisflies) are sister groups, sharing many similarities that are lacking in others; for example the females of both orders are heterogametic, meaning they have two different sex chromosomes, whereas in most species the males are heterogametic and the females have two identical sex chromosomes. The adults in both orders display a particular wing venation pattern on their forewings. The larvae in the two orders have mouth structures and glands with which they make and manipulate silk. Willi Hennig grouped the two orders into the superorder Amphiesmenoptera; together they are sister to the extinct order Tarachoptera. Lepidoptera descend from a diurnal moth-like common ancestor that either fed on dead or living plants.