. Elementary lessons on insects. Insects. HOW AN INSECT GROWS UP 31 22 times, but most insects molt from three to six times. The intervals between molts are technically called instars; and the larger divisions of the life history that are marked by great changes of form are called stages. The egg is the first stage. The second stage comprises a number of instars—five of them in the plant bug shown in the accompanying figure. Differences in size are not shown in this figure (but see figure 19 on page 53) for the smaller are magnified to the size of the larger for easy comparison. The changes of
. Elementary lessons on insects. Insects. HOW AN INSECT GROWS UP 31 22 times, but most insects molt from three to six times. The intervals between molts are technically called instars; and the larger divisions of the life history that are marked by great changes of form are called stages. The egg is the first stage. The second stage comprises a number of instars—five of them in the plant bug shown in the accompanying figure. Differences in size are not shown in this figure (but see figure 19 on page 53) for the smaller are magnified to the size of the larger for easy comparison. The changes of form are slight. Most marked is the development of wings. These appear on the back in the 3d instar, and increase progressively in the 4th and 5th. During all this growth period the bug is known as a nymph. Then comes the final molting, ushering in the adult stage (6 in the figure). The wings are now fully expanded, covering the body, and capable of flight. The antennae are enlarged. Sex organs are developed. Growth is ended, and the period of reproduction is at hand. The change of form from nymph to adult is often greater than that shown in the plant bug. The nymph of a dragonfly,. Fig. 12. The emergence of a dragonfly from its nymphal skin. ,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Needham, James G. (James George), 1868-1956. Springfield, Ill. , Baltimore, Maryland, C. C. Thomas
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Keywords: ., bookcentury1900, bookcollecti, bookdecade1920, booksubjectinsects
