. Les insectes utiles et nuisibles ; une introduction à l'étude de l'entomologie économique. Les insectes ; les insectes utiles ; les insectes nuisibles. 76 LES INSECTES UTILES ET NUISIBLES commence, un processus sur lequel il n'est pas décrire ici. Les cocons sélectionnés pour l'élevage sont divisés en mâles et femelles. Les cocons mâles sont plus légers, moins régulièrement avec extrémités arrondies, et s'est rétréci au milieu. Les sexes sont séparés, de sorte que les mâles peuvent ne pas être excité par l'odeur de la femme, qui met en place des luttes violentes pour la liberté. Un liquide jaune est libéré de l'intestin avant les papillons sont considérés comme mûrs. E

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. Injurious and useful insects; an introduction to the study of economic entomology. Insects; Beneficial insects; Insect pests. 76 INJURIOUS AND USEFUL INSECTS begins, a process which we shall not describe here. The cocoons selected for breeding are divided into males and females. The male cocoons are lighter, less regularly rounded at the ends, and narrowed in the middle. The sexes are kept apart, so that the males may not be excited by the odour of the female, which sets up violent struggles for liberty. A yellow fluid is discharged from the intestine before the moths are considered ripe. Then mating is permitted, and shortly afterwards the female begins to lay. The male moths perish early, but the females live several days, longer in cool weather than in hot. For at least three centuries it has been known that unfertilised females, occasionally though rarely, lay eggs, from which normal larvae proceed. The body of the moth is thick (especially in the female) and. Fig. 52.—Male silkworm moth. After Westwood. hairy. The feelers are pectinate (with comb-like projections), especially in the male. The fore wings are falcate (with a concave incision behind the tip). Both wings are cream- coloured, with faint transverse streaks of darker colour, and are extended when at rest; the legs are densely clothed with hair. The length of the female is about 21 mm., and the expanse of wings 43 mm. The moths occasionally utter a faint sound. Silkworms are subject to several infectious diseases, which have caused ruinous losses in the crowded rearing-houses. The story has often been told how, when the prosperity of large districts in the south of France was destroyed by pdbrine and flacherie, Pasteur, who had never treated any animal for any disease, was called in as adviser, how he learned the. 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 perfe

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