The chief work dealing with the systematic classification of plant lice is Buckton’s “Monograph of the British Aphidae,” published by the Roy. Society, London 1881. A number of new species have been described since by American entomologists in bulletins on Economic Zoology. Family 8. Snow-Flies. ALEURODIDAE. These are all very small delicate creatures; both sexes are furnished with two pairs of broad rounded wings with simple parallel veins, and are usually thickly covered with a mealy white dust from which they take their popular name of “Snow-Flies.” The head is broad, furnished with a three-jointed beak enclosing setae; seven-jointed antennae; and large reniform eyes, with an ocellus on either side above the eyes. The thorax is broad and the abdomen soft and rounded. The tarsi are two-jointed terminating in two claws at the extremities. The female lays her eggs in clusters on the under surface of the leaves, where the young larvae later on form regular oval, glassy tests of various colours, enclosed in which they feed and finally pupate. The adult insects have their short broad wings slightly expanded, and cluster together in threes and fours: but the moment their food plant is touched they fly out in a little cloud. They can, like the scale insects, be very easily introduced into a new country with their food plant, and several species, like _Aleurodes vaporariorum_ described by Westwood from Europe, have a wide range over America and this continent. The snow-flies are well represented in Australia, and several species do a considerable amount of damage to native shrubs, but on account of their delicate structure and small size they are difficult to collect, and harder to preserve when collected; if mounted on card they dry up, with nothing to determine them from but the wings, which have very few distinctive characters. The most satisfactory method of preserving them, is to drop the live insects into oil of cloves on a micro slip, when they usually open their wings and legs, and then make, with a little care, very fine objects when mounted in balsam; at times, however, the floury covering floats off the wings and body and sometimes clouds the mount.