. Principles of economic zoo?logy. Zoology, Economic. 126 BRANCH ARTHROPODA are beneficial, our crops will be the larger and more profitable, and our bodies more secure from disease. Classification.—Entomologists vary in their opinions as to the number of orders into which the Class Insecta should be divided. Packard's "Guide" (1883) gives eight orders, while Comstock's "Manual" (1895) and Kellogg's "American Insects" (1905) each give nineteen orders. Kellogg says, " In the first place the author believes that this classification^ best represents our present
. Principles of economic zoo?logy. Zoology, Economic. 126 BRANCH ARTHROPODA are beneficial, our crops will be the larger and more profitable, and our bodies more secure from disease. Classification.—Entomologists vary in their opinions as to the number of orders into which the Class Insecta should be divided. Packard's "Guide" (1883) gives eight orders, while Comstock's "Manual" (1895) and Kellogg's "American Insects" (1905) each give nineteen orders. Kellogg says, " In the first place the author believes that this classification^ best represents our present knowledge of insect taxonomy; in the second place,. Fig. 97.—Adult silkworm: 1, Head; 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, rings; 11, horn; 13, three pairs of articulated legs; 14, four pairs of abdominal or false legs; 15, a pair of false legs on the last ring. (Farmers' Bull. 165, U. S. Dept. of Agriculture.) this is the classification taught by nearly all the teachers of entomology in ; Students wishing to study insects in detail should consult either Comstock's or Kellogg's large work on insects. ORDER I. AP'TERA OR THYSANU'RA These are small or minute wingless insects which undergo no metamorphosis. The body is covered with hairs or scales. There are several pairs of rudimentary :il)dominal appendages, probably vestiges of abdominal legs in ancestors. The mouth parts are adapted for biting. " Their internal systems of organs have a segmental character corres]ionding to the external seg- mentation of the ;- They live in sugar boxes and pan- 1 Comstock's classification. - Kellogg, p. 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 Daugherty, Lewis Sylvester, 1857-; Daugherty, L. S. , Mrs. , 1859-. Philadelphia, London, W. B. Saunders
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