Dermaptera (Earwigs)
Elongate insects with typical biting mouthparts; superlinguae distinct; ligula 2-lobed. Fore wings modified into very short leathery tegmina devoid of veins; hind wings semicircular, membranous, with the veins highly modified and disposed radially. Aptero
- PDF / 1,383,284 Bytes
- 11 Pages / 439.37 x 666.142 pts Page_size
- 77 Downloads / 189 Views
II
DERMAPTERA (EARWIGS) Elongate insects with typical biting mouthparts; superlinguae distinct; ligula 2lobed. Fore wings modified into very short leathery tegmina devoid of veins; hind wings semicircular, membranous, with the veins highly modified and disposed radially. Apterous forms common. Tarsi 3-segmented. Cerci unjointed and almost always modified into heavily sclerotized forceps; ovipositor reduced ot absent. Metamorphosis slight.
The general appearance of these insects is well exemplified by the common European earwig, Forficula auricularia (Fig. 262), which also occurs in other parts of the Palaearctic region and has been introduced into N. and S. America, Australia, New Zealand and S. Africa. About 1200 species of Dermaptera are known and the majority show little marked variation in structure and habits. They are mostly nocturnal and many tropical species are attracted to light; during the day they hide away in the soil, under bark and stones, or among herbage. Except for Labia minor the European species rarely fly, even when (as in Forficula) they have well-developed wings. Two small sections of the order, represented by Hemimerus and Arixenia, have tended to adopt parasitic habits and differ somewhat from the majority. There are general accounts of the order by Beier (1958) and Gunther and Herter (1974). External Anatomy- There is a detailed comparative account by Giles (1963). The head (Henson, 1950; Strenger, 195oa) is more or less prognathous with a distinct gular sclerite and remnants of an ecdysial cleavage line, along part of which inflection has occurred to form a coronal and two post-frontal sulci. Epistomal, occipital and postoccipital sulci are present and the clypeus is divided into a sclerotized postclypeus and a membranous ~nteclypeus. There is a well-developed, imperforate tentorium (Hudson, 1947). Compound eyes are usually well-developed but ocelli are absent; the antennae have from 10 to so segments and bear chemoreceptor sensilla (Slifer, 1967). The mouthparts are of a generalized biting pattern with long, complete maxillae, each bearing a s-segmented palp. The labium has been variously interpreted but the characteristic two-lobed ligula seems to consist entirely of the paraglossae. The hypopharynx is two-lobed with 3 paired suspensory sclerites (Moulins, 1969). Popham (1959) recognizes ten major types of head and mouthparts within the order, depending on the degree of O. W. Richards et al., Imms’ General Textbook of Entomology © O. W. Richards and R. G. Davies 1977
DERMAPTERA (EARWIGS)
573
prognathism, the kind of food eaten and the associated modifications of the mandibles and maxillae. The thorax (Henson, 1953) has a large pronotum, the meso- and metatergum are normally subdivided in winged species and the metathorax has a postnotum. The metapleura are almost horizontally arranged and the sterna are broad, flat plates with well-defined apophyseal pits. Tegmina and wings are absent in Anisolabis, the Brachylabini and in Arixenia and Hemimerus, while the wings vary greatly in de
Data Loading...
