Elementary lessons on insects elementarylesson00need Year: 1928 30 ELEMENTARY LESSONS ON INSECTS quarters of the egg shell, stretches itself, and expands. Its skin hardens. Chitin is formed and it becomes, as we have seen (page 4) like a coat of mail; for it will not stretch very much. Therefore, with growth, it becomes too small and has to be cast off. The process is called molting. The chitinous outer layer of armor loosens from the under- lying new skin. Then it splits down the back, and the soft, limp, pale, but lusty and growing insect creeps out of it. Head and thorax first come up thr
Elementary lessons on insects elementarylesson00need Year: 1928 30 ELEMENTARY LESSONS ON INSECTS quarters of the egg shell, stretches itself, and expands. Its skin hardens. Chitin is formed and it becomes, as we have seen (page 4) like a coat of mail; for it will not stretch very much. Therefore, with growth, it becomes too small and has to be cast off. The process is called molting. The chitinous outer layer of armor loosens from the under- lying new skin. Then it splits down the back, and the soft, limp, pale, but lusty and growing insect creeps out of it. Head and thorax first come up through the rent then the legs and abdomen are withdrawn. After each molt a sudden expansion and increase of size oc- curs, while the skin is new and stretchable. Then it hardens again. The number of molts undergone by different kinds of insects in their growing up varies, but is rather constant for each kind. One common stonefly, (Nemoura) moults Fig. 11.—The developmental stages of a plant bug, Tropidosleptes cardinalis (after Leonard). Figures 1 to 5 are the successive nymphal ins tars; 6 is the adult.
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