The Fauna of British India, including Ceylon and Burma / edited by A.E. Shipley. Dermaptera (Earwigs) / by Malcolm Burr.

Date:
1910
Catalogue details

Licence: In copyright

Credit: The Fauna of British India, including Ceylon and Burma / edited by A.E. Shipley. Dermaptera (Earwigs) / by Malcolm Burr. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

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    INTRODUCTION. depressed, with a transverse elliptical cross-section ; the side* may be parallel (Labidum, Elaunon), or gently dilated about the middle {Anisolabis and certain species of Forjiculci); in the Apachyidce and in Flatylahia the body is remarkably depressed,, being as flat as cardboard. In the female the abdomen almost in- variably tapers somewhat towards the hinder end. There are in all ten segments; excluding the last, there are nine, but in the female only seven are visible, as the eighth and the ninth are aborted and reduced to mere specks of chitin which can only be detected upon dissection. In Forcipida the sides o£ certain segments are furnished with ridges, keels or long spines ; in certain species of Fsalince the sides of the segments are produced posteriorly to a more or less acute angle and are generally striated or furrowed. This struc- ture affords useful specific charactei's. In Eparchus the sides of the abdomen are studded with a series of knobs or tubercles. In the Lahidurince the posterior margins of the segments are milled. All these structures are almost or entirely undeveloped in the females. In many genera, as in the Forjiculidce, the Labiidce, and others, the second and third abdominal segments have at the sides tubercular folds in the integument, which are stink-glands. The segments are closely imbricated into each other ; when the abdomen is distended, the membrane holding the chitinous plates together may be seen with the minute perforation of the tracheal pores. The texture of the chitin varies from smooth to granular. The ventral surface is flat, and generally smoother and paler than the dorsal surface. The last dorsal plate, or sclerite, is large and ample, and as it presents a great variety of form and of armature it olfers valuable discriminative characters; it is invariably more simple and almost always narrower in the female than in the male. The penultimate ventral sclerite is vei'y large, so that the last ventral sclerite is almost or entirely hidden ; when disclosed by the removal of the penultimate it is shown to be separated into two portions by a median fissure so as to permit the passage of the faeces and the reproductive cells. The outline of the penulti- mate segment is usually slightly different in the two sexes and offers useful generic and specific characters. The pygidium is a chitinous organ existing between the roots of the forceps and the edges of the apical abdominal segments; it is sometimes hidden, but is as frequently protruded. It assumes a great variety of shapes in both sexes, thus offering very useful specific characters. In the Apachyidce the last abdominal segment is produced without any apparent suture or joint into a depressed lobe termed the anal process ; as it appears to be a mere extension of the anal segment, it is probably not homologous with the pygidium, which is a distinct organ. . The forceps are the most characteristic organs of earwigs. Ihey consist of a pair of more or less elongate, hard unsegmented