The popular and scientific names of these insects refer to the brilliant metallic blue, green, golden or copper coloured tints of their armour-plated bodies, which are also covered with coarse punctures, finest upon the abdomen. They are stout thickset wasps with short curled antennae and large eyes; the thorax is broad and closely attached to the abdomen, the latter composed of from three to five segments, the first generally much shorter than the second, with the last toothed along the hind margin, and characteristic of the different species; the under-surface of these plates is concave, with the tip of the abdomen produced into a tubular process, so that when alarmed the wasp can curl her body round into a ball, protected on all sides by the armour-like integument; and as she lays her eggs in the nests of other wasps and bees, and is sometimes caught in the act, this habit is probably a wise provision of Nature which enables her to resist the sting of the lawful nest maker. Some of the earlier observers called them “Cuckoo Wasps,” under the impression that their larvae, when hatched out in the nests of hunting wasps or bees that filled the cells with insects or bee bread, fed upon the stored food supplies, but later researches show that, though the egg of both the lawful occupant and the intruder may be deposited in the cell, the latter does not hatch until the former has devoured all the food placed there by his mother and is ready to pupate; then the ruby wasp baby comes out, attaches itself to the full fed larva beside it, and sucks him dry, pupating in his skin. Most of our species that I have bred out are parasitic in the clay nests of the smaller Mason Wasps, _Odynerus_ and _Alastor_, though in Europe many species live in the nests of bees. The perfect insects are generally found crawling over or flying round old fences or stumps and dead trees in the hottest part of the day. Our species were described by F. Smith in 1874 in his revision of the family, in the Transactions of the Entomological Society of London; a few others have since been added to the list by Mocsáry, who monographed the Chrysididae in 1889; and Gribodo in the Annals of the Mus. Geneva, 1879. No member of the typical Genus _Cleptes_ common in Europe and America is recorded from Australia; but two well defined species of the beautiful ruby wasps of the Genus _Stilbum_ that has a world wide range are described, _Stilbum splendidum_ confined to Australia and New Caledonia, and _Stilbum amethystinium_, found also in Asia, Africa and America. The great Genus _Chrysis_, which contains over 600 described species, is represented here by about 27 species. Family 11. Hatchet-bodied Wasps. EVANIIDAE.