. Schädliche und nützliche Insekten; eine Einführung in das Studium der ökonomischen Entomologie. Insekten; nützliche Insekten und Schädlinge. 76 schädliche und nützliche Insekten beginnt, ein Prozess, den wir hier nicht beschreiben. Die Kokons für die Zucht ausgewählt werden in Männer und Frauen unterteilt. Die männlichen Kokons sind leichter, weniger regelmäßig an den Enden abgerundet und in der Mitte verengt. Die Geschlechter sind getrennt, so dass die Männchen können nicht durch den Geruch des weiblichen, der heftigen Kämpfe für Freiheit begeistert sein. Eine gelbe Flüssigkeit aus dem Darm entlassen wird, bevor sie die Motten sind reif. Th

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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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• bookcentury1900
• bookdecade1900
• booksubjectinsects
• bookyear1902