Elementary textbook of economic zoology Elementary textbook of economic zoology and entomology . elementarytextbo00kell Year: [c1915] SLIME SLUGS, MYRIAPODS AND INSECTS 143 shell or chorion. But a small hole, called micropyle, is left at one pole in both these coverings, and through this a sper- matozoan enters the egg while it is in the vagina, or a special posterior part of it called the bursa copidatrix. The organs of the male that produce the spermatozoa are called testes, and correspond in position and function to the ovaries of the female. They are also composed of many tubules, but the
Elementary textbook of economic zoology Elementary textbook of economic zoology and entomology . elementarytextbo00kell Year: [c1915] SLIME SLUGS, MYRIAPODS AND INSECTS 143 shell or chorion. But a small hole, called micropyle, is left at one pole in both these coverings, and through this a sper- matozoan enters the egg while it is in the vagina, or a special posterior part of it called the bursa copidatrix. The organs of the male that produce the spermatozoa are called testes, and correspond in position and function to the ovaries of the female. They are also composed of many tubules, but they are closely pressed together to form a small solid ovate mass. From each testis runs a duct, the vas deferens, through which the spermatozoa pass to reach the single ejaculatory duct, from which they are expelled by the male at mating. TYPES or MOUTH-PARTS Corresponding to the great vari- ety of food taken by insects is a great variety in structure of mouth- parts. The mouth-parts of the honey-bee, which laps up flower nectar, are very different from those of the grasshopper, which bites off and chews green leaves. And very different from either of mdlifica, reproductive organs, .v • ,1 ,1 sting and poison glands of these, again, are the mouth-parts que£n> dors£ view 6 (Greatiy of a butterfly or moth, or of a magnified; after Snodgrass.) mosquito, or a squash-bug. To the economic entomologist a knowledge of the kind of mouth-parts possessed by any insect pest is very important. For on the structure of its mouth will depend largely the kind of artificial remedy which must be devised to kill it. For ex- ample, if an insect pest of fruit trees has a piercing and sucking mouth, then spraying the surfaces of leaves with an arsenical poison will do little good, for it gets its food, plant sap, from the interior of the leaf or stem. But if it has a biting and chew- ing mouth then such a poison sprayed over the leaves may be FIG. 59.—Honey-bee, Apis
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