_Other Apparatus._--Much of the breeding of insects can be done with the simplest apparatus, and for the rearing of Microlepidoptera, Gall-insects, and the keeping of cocoons and chrysalides of small species, nothing is more convenient than a medium sized test-tube, the end of which may be plugged with cotton. I have recently successfully carried over the winter the larva of _Sphecius speciosus_, which had been removed early in the fall from its earthen pod or cocoon, the larva transforming to a perfect pupa in the spring. In this case the test tube was plugged with cotton and inserted in a wooden mailing tube to exclude the light. Smaller jars with glass covers or with a covering of gauze may be employed for most insects, with the advantage of occupying comparatively little space and of isolating the species under study. [Illustration: FIG. 125.--Root cage: _a_, frame with slide removed; _b_, movable slide; _c_, top view (original).] Long glass tubes, open at both ends, are useful in many other ways, especially in the rearing and study of the smaller hypogean insects or those which bore and live in the stems of plants. An infested stem cut open on one side and placed in such a tube will generally carry any insect that has ceased feeding, or any species like the wood-boring bees which feed upon stored food, successfully through their transformations; while root-lice may be kept for a lengthy period upon the roots in such tube, providing a portion of the root extends outside of the tube and is kept in moistened ground or water. In all such cases these tubes, with their contents, should be kept in the dark, either in a drawer or else covered with some dark material which can be wound around or slipped over them, and the ends must be closed with cotton or cork. The rearer of insects will frequently experience difficulty in carrying his pupae through the winter, and, even though ordinary precautions are taken, the mortality will frequently amount to 50 per cent of the specimens. Mr. H. Bakhaus, of Leipzig, thus describes a device which is substantially the base of the vivarium shown on page 114. "The base consists of a round plate of strong zinc, with two vertical rims, an inch high, placed one within the other, an inch apart, and soldered to the basal plate so that the outer one is water-tight. The inner rim must be perforated with small holes as close to the bottom as possible. The space inside the inner rim must be filled with fine sand, on which the pupae should be laid. The space between the two rims is then filled with water, which, finding its way through the holes in the inner rim to the sand, causes the necessary moisture. Over the whole is put a bell-shaped cover of wire gauze, which must fit tightly over the outer rim. In this receptacle the pupae remain untouched, and receive fresh moisture, as above indicated, if required by the drying of the sand."