The presence of ants is probably of great value to the larvae, for they keep parasitic insects and birds from molesting them. When full grown they sling themselves to the twigs to pupate, and are often so numerous that the branches are covered with pupae hanging like bunches of grapes. The butterfly measures nearly 2 inches across the wings, which on the upper surface are black on the margin, with the rest pale metallic blue shading into white in the centre; the hind pair are scalloped and produced into fine feathery tails with spots of dark orange yellow at the base; the under side is pearly grey, banded and spotted with black. _I. ictinus_, with identical habits, about the same size, takes the place of this species in the inland districts. _Pseudalmenus myrsilus_ is a handsome little butterfly with the centres of the wings deep orange divided with dark nervures, and the hind pair with long black tails; it is found from Tasmania to the southern districts of N.S. Wales. The last species of this family, _Liphyra brassolis_, is only found in North Queensland; its larvae live and pupate in the arboreal nests of the “Green Tree-ants.” An interesting account of the life history of this butterfly is given by Dodd in the “Entomologist” 1902. Family 4. The Whites and Yellows. PIERIDAE. The members of this family are popularly known as “Whites” and “Yellows” on account of their prevailing colours. Both sexes have six perfect legs, and are butterflies of moderate size, with the hind wings rarely crenulated or produced into tails. Their larvae are slender, hairy caterpillars with small heads, and are often gregarious in their habits; the pupae are sharply angulated to each extremity, attached both by the tail, and a silken girdle round the body of their food plant. In Miskin’s Catalogue 34 species are listed, contained in 7 genera; Waterhouse reduces them to 31 species, and discards several well-known genera. The Genus _Terias_ contains all the small “Yellows,” which are low flitting, dainty, little butterflies found in the tropical jungle, but equally at home in the far western scrubs and open forest land. _Terias smilax_, our smallest species, is common about Sydney, and has a wide range both north and south from Adelaide to Rockhampton. It is bright yellow, with the black markings in the fore wings extending to the tips of the hind pair. The Mottled Yellow, _T. hecabe_, is much larger than the last; is of a bright yellow colour with the black markings coming round to the edge of the hind wing and swelling out into a rounded patch; the hind wings are lightly edged with black, and on the under side are thickly mottled with yellowish brown spots. It extends from Sydney to Queensland, and has a wide range out northward and eastward among the islands.