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TERZI

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Originally appearing in Volume V13, Page 262 of the 1911 Encyclopedia Britannica.
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TERZI. -_. After Howard, Year Book U.S. Dept. Agr., 1894. into a process or hood-like structure which may extend far behind the tail-end of the abdomen. Two other allied families, the Cercopidae and Jassidae, are more numerously represented in our islands. The young of many of these insects are green and soft-skinned, protecting themselves by the well-known frothy secretion that is called " cuckoo-spit." In all the above-mentioned families of Homoptera there are three segments in each foot. The remaining four families have feet with only two seg- Pmm Osborn (after Deane), meets. hey are of B:dl. 5 (N.S.), Div. Ent. very great zoological G.S. Dept. Agr. interest on account of ( Pediculus vestimenti). their life-history—par- Magnified. thenogenesis being of normal occurrence among most of them. The families Psyllidae or " jumpers ") with eight or ten segments in the feeler and the Aleyrodidae (or " snowy flies ") distinguished by their white mealy wings, are of comparatively slight importance. The two families to which special attention has been paid are the Aphidae or plant-lice (" green fly ") and the Coccidae or scale-insects. The aphids (fig. II) have feelers with seven or fewer distinct segments, and the fifth abdominal From Osborn (after segment usually carries a pair of tubular pro- Schiodte), Ball., (IV .S.), cesses through which a waxy secretion is dis- Div. Ent. U.S. Dept. charged. Tha sweet " honey-dew," often Agr. . sought as a food by ants, is secreted from the FIG. 15. — Pro-intestines of aphids. The peculiar life-cycle in boscis of Pediculus. which successive generations are produced Highly magnified. through the summer months by virgin females —the egg developing within the body of the mother—is de-scribed at length in the articles APHIDES and PHYLLOXERA. The Coccidae have only a single claw to the foot; the males (fig. 12 a) have the fore-wings developed and the hind-wings greatly reduced, while in the female wings are totally absent and the body undergoes marked degradation (figs. 12, e, 13, a, b). In the Coccids the forma- tion of a protective waxy secretion—present in many genera of Homoptera—reaches its most extreme development. in some coccids —the " mealy-bugs " (Dactylopius, &c.) for example—the secretion forms a white thread-like or plate-like covering which the insect carries about. But in most members of the family, the secretion, united with cast cuticles and excrement, forms a firm " scale," closely attached by its edges to the surface of the plant on which the insect lives, and serving as a shield beneath which the female coccid, with her eggs (fig. 13 a' and brood, finds shelter. The male coccid passes through a passive stage (fig. 4) before attaining the perfect condition. Many scale-insects are among the most serious of pests, but various species have been utilized by man for the production of wax (lac) and red dye (cochineal). See ECONOMIC ENTOMOLOGY, SCALE-INSECT. ANOPLURA The Anoplura or lice (see LOUSE) are wingless parasitic insects (fig. 14) forming an order distinct from the Hemiptera, their sucking and piercing mouth-organs being apparently formed on quite a different plan from those of the Heteroptera and Homoptera. In front of the head is a short tube armed with strong recurved hooks which can be fixed into the skin of the host, and from the tube an elongate more slender tucking-trunk can be protruded (fig. 15). Each foot is provided with a single strong claw which, opposed to a process on the shin, serves to grasp a hair of the host, all the lice being parasites on different mammals. Although G. Enderlein has recently shown that the jaws of the Hemiptera can be recognized in a reduced condition in connexion with the louse's proboscis, the modification is so excessive that the group certainly deserves ordinal separation.
End of Article: TERZI
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