. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. HYMENOPTERA. 593 In connection with the great power of flight, the longitudinal tracheal trunks give rise to vesicular dilatations, of which two at the base of the abdomen are conspicuous by their size. The female sexual organs usually possess very numerous (up to one hundred) many-chambered egg tubes, and a large receptaculum seminis with accessory glands. A special bursa copulatrix is absent (fig. 488). When a sting is developed, filiform or branched poison glands with a common reservoir and a duc
. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. HYMENOPTERA. 593 In connection with the great power of flight, the longitudinal tracheal trunks give rise to vesicular dilatations, of which two at the base of the abdomen are conspicuous by their size. The female sexual organs usually possess very numerous (up to one hundred) many-chambered egg tubes, and a large receptaculum seminis with accessory glands. A special bursa copulatrix is absent (fig. 488). When a sting is developed, filiform or branched poison glands with a common reservoir and a duct opening into the sheath of the sting, are present. In the male sex the ducts of the two testes are connected \vith two accessory glands, while the common ductus ejaculatorius ends with a large protrusible penis. With the exception of the leaf-wasps (Tenthredinidce), and wood- wasps [Uroceridce), the larvae are apodiil and live either parasitically in the body of insects (the PtQromalince pass through various larval stages, undergo- Y) ing a kind of Or hypermetamor- ^^^>=^ """"^ ^^^nfiiT^'^^ M phosis) or in plants, or in brood spaces (cells) formed of animal and vege- table substances. The former, like the caterpillars of the butterflies, possess, besides the six thoracic legs, six to eight pairs of abdominal legs, and live free on leaves; the latter are grub-like, find the nutritive material in their cells, and are in part fed during their growth. Almost all—, the larvse of bees and wasps—possess a small retractile head with short mandibles and pointed pieces (maxillse and labium). The anus is not developed, for the stomach is blind and does not communicate with the hindgut, which receives the Malpighian tubules. Most of the larvae, when they enter the pupal stage, spin an irregular invest- ment or a firmer cocoon of silk-like fibres. The larvae of bees and wasps then soon undergo a moult (when they get rid of their excrementitious matters), and
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanimals, bookyear1892
