They insert their eggs in the stems of water plants, which the female pierces with her sharp ovipositor; and some European species are known to hibernate in the mud at the bottom of the pools and water-holes. Several species are common in our ponds and creeks, and are savage little creatures destroying many other aquatic insects, and even small fish. _Enithares bergrothi_ is our common species with a very wide range over Australia. In their larval state they are silvery white in appearance, but as the elytra develop and cover the back they change to dark brown, mottled, shining creatures, with the body measuring about ⅓ of an inch in length. Family 14. Water-Boatmen. CORIXIDAE. The members of the family CORIXIDAE differ from the “Back-swimmers,” though both are often called “Water-Boatmen,” in having the fore tarsi flattened, fringed with hairs on the edges, but without any claws, while the head overlaps the thorax. They swim the opposite way (with the back upwards), and are flattened on the ventral surface. One or more species may be often captured with a net in the same situations as the members of the former group. _Corixa eurynome_, described by Kirkaldy, is our common species found in creeks and water-holes all over Australia. It measures over ⅓ of an inch in length, with the scythe-shaped hind legs projecting behind; it is of a uniform chocolate brown colour on the dorsal surface, except the space between the eyes, which with the legs and ventral surface are dull yellow. The large flattened lead-coloured eyes are almost triangular. Sub-Order II.--HOMOPTERA. This sub-division was formed to include some families of haustellate insects which, though closely related to the true plant bugs, have well-defined characteristics that bring them into a natural Sub-Order of their own. They all have the typical suctorial mouth, but the front of the head is much inflexed so as to be in contact with the coxae. The front pair of wings are not true elytra, being generally membranous, and are usually referred to as tegmina. Some, like the aphids, have both pairs of wings delicate and transparent; while in the scale insects, the females are always wingless, and the male is provided with a single, imperfectly veined pair only. When at rest, the wings in the typical homoptera are folded over the back like a roof, forming a ridge. All the families are well represented in Australia, except the _Aphidae_, of which no indigenous species have been recorded, the _Psyllidae_ with similar habits taking their place, at any rate in our western scrubs. Like true hemiptera, they each undergo an incomplete metamorphosis, some moulting many times before the final ecdysis; and all feed in the immature and perfect state on the sap of plants.