These handsome flower wasps are closely allied to the members of the previous family, as they have similar wingless females of such peculiar shapes that, if examined alone, they would never be taken for the consorts of the large wasp-like _Thynnus_, with its long stout antennae, well developed legs, and large powerful wings. The males fly about the flowers of leptospermum and eucalypts, and when captured bite and pretend to sting by turning up the tip of the abdomen, which ends in a horny, harmless process. Fortunately, when hunted for in the summer, most of our commoner species can be taken _in copula_ with the smaller female, with which he flies about quite easily; when caught the female immediately detaches herself and falls to the ground, where she crawls out of sight, so that care must be taken by the collector to keep each pair captured in a box by themselves, or else when once mixed up it is impossible to determine unknown species. Australia is the headquarters of this group, for of about 400 described species, 300 are peculiar to this country; the others are chiefly confined to Brazil and Chili in South America, with a few from Asia and the Islands. Smith has described a great number in the British Museum Catalogues; Westwood others; and Guerin those collected during the Voyage de Coquille in 1830; but as many of these were determined from single specimens of one sex, it is certain that when a collection of sexed specimens can be compared with the types, the number of species will suffer considerable reduction. Nothing definite is known about the earlier stages of their development; I have however obtained cocoons composed of a stout silken case enveloped in a thin outer second papery covering, oval in form, with a nipple-like projection at the extremity, from which I have bred one of our large species. These cocoons are buried several inches in the ground like those of the _Scolias_, so that the females, which are furnished with short, stout, spiny legs well adapted for digging, probably lay their eggs in lamellicorn larvae living in the loose soil.