"In the hands of the careful breeder an insect may be secured against its numerous natural enemies and against vicissitudes of climate, and will, consequently, be more apt to mature than in a state of nature. The breeding of aquatic insects requires aquaria, and is always attended with the difficulty of furnishing a proper supply of food. The transformations of many others, both aquatic and terrestrial, can be studied only by close and careful outdoor observation. But the great majority of insect larvae may be reared to the perfect state indoors, where their maneuverings may be constantly and conveniently watched. For the feeding of small species, glass jars and wide-mouthed bottles will be found useful. The mouths should be covered with gauze or old linen, fastened either by thread or rubber, and a few inches of moist earth at the bottom will furnish a retreat for those which enter it to transform and keep the atmosphere in a moist and fit condition. _The Breeding Cage or Vivarium._--"For larger insects I use a breeding cage or vivarium which answers the purpose admirably. It is represented in figure 123, and comprises three distinct parts: First, the bottom board _a_, consisting of a square piece of inch thick walnut with a rectangular zinc pan _ff_, 4 inches deep, fastened to it above, and with two cross pieces _gg_ below, to prevent cracking or warping, facilitate lifting, and allow the air to pass underneath the cage. Second, a box _b_ with three glass sides and a glass door in front, to fit over the zinc pan. Third, a cap _c_, which fits closely on to the box, and has a top of fine wire gauze. To the center of the zinc pan is soldered a zinc tube _d_ just large enough to contain an ordinary quinine bottle. The zinc pan is filled with clean sifted earth or sand _e_, and the quinine bottle is for the reception of the food plant. The cage admits of abundant light and air, and also of the easy removal of excrement or frass which falls to the ground; while the insects in transforming enter the ground or attach themselves to the sides or the cap, according to their habits. The most convenient dimensions I find to be 12 inches square and 18 inches high: the cap and the door fit closely by means of rabbets, and the former has a depth of about 4 inches to admit of the largest cocoon being spun in it without touching the box on which it rests. The zinc pan might be made 6 or 8 inches deep, and the lower half filled with sand, so as to keep the whole moist for a greater length of time."