The 1st instar larva of Ogygioses caliginosa Issiki & Stringer is described from Taiwan. This is the first information on larvae of the family Palaeosetidae, being only the second family in Hepialoidea where such data are known. Special features of Ogygioses larvae include a prognathous head with a clypeus protruded over the labrum, stemmata numbering only 3, and compact antennae recessed into circular cavities. Also unusual are the circular spiracles with encircling rings. Larval characters conform to Hepialoidea, although more specialized. In comparison to Palaeosetidae larvae, larval characters are summarized for other families of primitive Lepidoptera where larvae are known.
