For the most part the directions for collecting Coleoptera will apply to this order of insects equally well, especially so far as concerns the first section of the order (Heteroptera), and the higher families of the second section (Homoptera). A few directions may be given for the lower forms, including the Aphididae, Coccidae, Aleurodidae, and Psyllidae, and the suborder Parasita, including the degraded forms which infest man and the lower animals. The Plant-lice or Aphides should always be collected in connection with their food-plants, and it is very essential also to collect the same species at different seasons of the year to obtain the different forms or generations, which frequently present very marked differences. It is also very necessary to secure the winged forms, which are usually produced toward autumn, and without which the species are not easily identified. The Bark lice or Scale-insects should also be collected in connection with the leaves or twigs which they infest. The males of these insects are minute and, as a rule, two-winged, resembling small gnats, and may be bred from the male scales. The females are for the most part stationary, being fixed to the plant by the protecting, waxy, excretion or scale. The Flea-lice (_Psyllidae_) frequently produce galls, and these should always be collected with the insect architects. Some species do not produce galls, and may be collected by sweeping. The Hackberry is infested by large numbers of species of Psyllids, and these produce a great variety of interesting galls. The Aleurodidae (Fringe-scales) are delicate insects, and easily injured in the taking; they are therefore best reared from their stationary and fringed larvae and pupae, which occur on the leaves of many plants. Leaves bearing the latter should also be collected and pinned or preserved in alcohol. The Parasita, the lowest representatives of the order, may be obtained from the domestic and wild animals which they infest. [Illustration: FIG. 76.--The Bed-bug (_Acanthia lectularia_). _a_, young; _b_, adult--enlarged.] [Illustration: FIG. 77.--The Short-nosed Ox-louse (_Haematopinus eurysternus_). _a_, female; _b_, rostrum; _c_, ventral surface, last segments of male; _d_, female; _e_, egg; _f_, surface of egg greatly enlarged.] COLLECTING DIPTERA. [Illustration: FIG. 78.--Ox Bot-fly (_Hypoderma bovis_) enlarged. (After Brauer.)] [Illustration: FIG. 79.--The Collecting Shears. (After Kiesenwetter.)] [Illustration: FIG. 80.--A Bee-fly (_Anthrax hypomelas_). _a_, larva from side; _b_, pupal skin protruding from cutworm chrysalis; _c_, pupa; _d_, imago--all enlarged.]