. Elementary zoology. Zoology. *&. which sing so shrilly from the trees, the seventeen-year cicada (Cicada septendecivi) (oftentimes called locust) being the best known of this family. Its eggs are laid in slits cut by the female in live twigs. The young, which hatch in about six weeks, do not feed on the green foliage, but fall to the ground, burrow down to the roots of the tree and there live, sucking the juices from the roots, for Fig. 66.—The seventeen-year cicada, Ci- sixteen years and ten or cada septendecim; the specimen at left i r \\TU showing sound-making organ, v. p., ven- eieve
. Elementary zoology. Zoology. *&. which sing so shrilly from the trees, the seventeen-year cicada (Cicada septendecivi) (oftentimes called locust) being the best known of this family. Its eggs are laid in slits cut by the female in live twigs. The young, which hatch in about six weeks, do not feed on the green foliage, but fall to the ground, burrow down to the roots of the tree and there live, sucking the juices from the roots, for Fig. 66.—The seventeen-year cicada, Ci- sixteen years and ten or cada septendecim; the specimen at left i r \\TU showing sound-making organ, v. p., ven- eieven months. When tral plate; *, tympanum. (From speci- about to become adult, men.) - • i 1 the young cicada crawls up out of the ground and clinging to the tree-trunk molts for the last time, and flies to the tree-tops. The plant-lice {Aphididce) are small soft-bodied Hemiptera which have both winged and wingless indi- viduals. In the early spring a wingless female hatches from an egg which, laid in the preceding fall, has passed the winter in slow development. This wingless female, called the stem-mother, lays unfertilized eggs or more often perhaps gives birth to live young, all of which are similarly wingless females which reproduce partheno- genetically. This reproduction goes on so rapidly that the plant-lice become overcrowded on the food-plant and then a generation of winged * individuals is produced from * It has been shown by experiment that the winged individuals, which are able to leave the old food-plant and scatter over new plants, do not appear until the food-supply begins to run short. At the insectary of Cornell Uni- versity ninety-four successive generations of wingless individuals were bred,. 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 Kellogg, Vernon L. (Vernon Lyman), 1867-1937. Ne
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1902
