Another form of larva glass can easily be made out of a large glass jar if you know how to cut off the bottom, or of a chemist's bell jar which is open both at top and bottom. In this case the bottle of water and the soil are arranged as before in a pan of unglazed earthenware, and then covered over with the glass. This is shown in fig. 58, and is an exceedingly convenient larva house, since the lifting of the glass enables you to get at the insects without any trouble. [Illustration: FIG. 59.--A LARVA CAGE.] Wood larva cages are very commonly used for the larger species after they have attained a fair size and require more food than can be stocked in bottles and glasses. These cages have glass fronts, either sliding or in the form of a hinged door, and sides of perforated zinc. They are kept in stock by all dealers in entomologists' requisites, but equally useful ones are easily constructed. If you select a box of suitable size at the grocer's, cut out large pieces from the lid and sides with a fret saw, and fix in the glass and zinc, you will have a cage that will answer all purposes. The internal arrangements consist of a shallow tray filled with soil, in which stands the bottle of water for the food, and a layer of moss sufficiently high to cover the bottle completely. A series of such boxes standing on end on a shelf, or hanging on a wall, will form a very satisfactory nursery for your pets, and will occupy but little space. We have already observed that some larvae burrow into soil when about to change, while others creep to a sheltered corner, or suspend themselves from the food plant itself. It will be seen that the larva cage just described supplies all these demands, and care must be taken not to disturb the occupants while they are undergoing their metamorphoses. Those that suspend themselves on the food plant should be allowed to remain where they have fixed themselves, and when it is necessary to remove the stale food in order to give a fresh supply to the later larvae, let it be fixed in an airy place where it can be watched till the perfect insects emerge. Those which suspend themselves on the sides or top of the cage, or spin cocoons in the corners, should never be disturbed unless you are greatly in want of the same cage for the accommodation of another brood; and even then it is possible that their presence will not in any way interfere with the new species. But if their removal becomes a necessity, let it be carried out as carefully as possible, and not until the change to the pupal stage is known to be complete. The species that burrow into the soil or bury themselves in the moss need never be disturbed till the rearing season is quite over, and then they may be transferred to a box specially kept for the accommodation of pupae.