Though the Hessian Fly, _Cecidomyia destructor_, is not known in Australia it has been introduced into New Zealand, and in the United States of America is one of the most serious pests that the wheat farmers have to fight. This gnat deposits her eggs under the sheath of the growing wheat stalks; the larva sucks up the sap, so that the ear is impoverished and no grain forms in the head; and when they are numerous the greater part of the crop is destroyed. Family 2. Shade Midges. MYCETOPHILIDAE. These small flies, popularly known as “Midges,” are placed by Skuse in four well defined families, which I place under the one heading as their habits are very similar. The SCIARIDAE are the typical “Shade midges” infesting forest country; their larvae live under dead bark or decomposing leaves and are slender, cylindrical, semi-translucent maggots, white or pale yellow in colour, with the body composed of 13 segments including the head. The perfect insects have moderately long, curved, many jointed antennae; two ocelli; long slender legs; and the wings often clouded. Skuse has described 42 species in this group, all of which with one exception he placed in the typical Genus _Sciara_; these have the wings longer than the abdomen, the surface of them microscopically pubescent, and the wing-lobes more or less developed. The MYCETOPHILIDAE are popularly known as “Fungus-midges” from the fact that the larvae, which are slender white maggots attenuated at both extremities, and with horny heads, are often found feeding upon the juices of fungi; some spin silken webs under which they live, and a few are said to be luminous. They are small flies with beautifully marked wings in many species, and have slender antennae; 3 ocelli; and a short proboscis; the rather long legs have the coxae elongated and are furnished with spurs upon the tibiae; the wings, without a discoidal cell, have more veins than those of the Gall-gnats. Walker described 4 species (Insecta Saundersiana 1856); to which Skuse added 31 new species. _Lyomya setiosicaudata_ was described by Skuse from the neighbourhood of Sydney in the Genus _Acrodicrania_, but it has an extended range: I have taken it with a sweeping net about Inverell N.S. Wales. It measures about ⅙ of an inch in length; has a shining head and thorax; abdomen black, and variegated black and yellow legs.