The PIRATINAE comprise some of the so-called “Assassin bugs”; in colour most of them are dark brown or black, marked with dull yellow; they hide under stones in the daytime, and often in summer come flying to the lights in the house at night, when, if carelessly handled they can inflict a very severe stab with the beak. _Pirates ephippiger_ is one of our largest species, measuring over ¾ of an inch in length. It is of a uniform dull black, with the stout legs reddish brown in colour, and there is a heart-shaped patch of bright yellow behind the scutellum. The prothorax is narrow, smooth and rounded, with a constriction separating it distinctly from the broader mesothorax which is also smooth and rounded. _P. flavopictus_ is a very much smaller species, black in colour, with the yellow blotch behind the scutellum. The whole insect is clothed with fine hairs. It is a common species in New South Wales, and has a wide range over the southern part of the continent. Twelve other species of this large genus are described from Australia and Tasmania. The HARPACTORINAE is the largest division of this family, and comprises both the large spiny “assassin bugs” that crawl about among the foliage or hunt over the tree trunks, and some typical forms, most plentiful in tropical countries. _Havinthus depressus_ is a small, flat, dark brown species, under ½ an inch in length, with the outer margins of the body mottled with dull red. _H. rufovarius_ is a larger bug of a general black colour, with the head, front of thorax, legs, bases of the elytra, and under surface of the abdomen marked with deep red. The body is rugose and clothed with short stiff hairs. It has a wide range over Australia; and a very large variety, with blood red markings, from Kalgoorlie (W.A.), measures over an inch in length. The members of the Genus _Gminatus_ are peculiar to Australia, and are found hunting over tree trunks and flowers. The body is somewhat constricted behind the thorax, broadening towards the rounded apex. _Gminatus nigroscutellatus_, over ½ an inch in length, is of a general bright red colour, with the legs and scutellum black, and the apical areas of the elytra rich metallic bronze. The dorsal surfaces of the head and thorax are ornamented with a number of tubercles or spines. _G. australis_, slightly smaller and more slender than the previous one, differs in having the head black; the prothorax black and furnished with two pairs of black spines, and the shorter spines in the rest of the thorax tipped with black. The Bee Killer, _Pristhesancus papuensis_, is a large brown bug, nearly 1¼ inches in length, and thickly clothed with short buff hairs. The outer edge of the thorax is produced into erect blunt tubercles, seven in number, forming an angle on the outer margins. The dorsal surface of the abdomen is very concave; the folded elytra lie sunk well below the sides of abdomen, which are flanged and raised.