The Mantidae are an extensive family of Orthoptera, showing extreme variety in the shapes and outlines of the body, and characterised by the very remarkable front legs; the function of these legs being to seize and hold their prey, which consists of living Insects, Mantidae being carnivorous and highly voracious.
The labium is deeply divided, each half exhibiting a very near approach to the structure of a maxilla; there is a large membranous lingua reposing on the inner face of the lower lip. The head is quite free from the thorax, its front part being deflexed, and even somewhat inflexed, so that the mouth is directed downwards and somewhat backwards: it is very mobile, being connected to the thorax by a comparatively slender neck, which is, however, concealed by the pronotum. There are two large, prominent eyes, the antennae are frequently very slender, but they sometimes differ according to sex, and in some genera are pectinate in the male; just above and between their insertion are three ocelli placed in a triangle, two above, one below; between the antennae and the clypeus there is an interval called the scutellar space. In some forms of Mantidae the head assumes most extraordinary shapes; the eyes may become elongate and horn-like; there may be a projection between them bearing the ocelli, and attaining occasionally a great length; the scutellar space also may have a remarkable development, the whole thus forming a peculiar ornamental structure, as in Fig. 136.
Fig. 135.—Deroplatys sarawaca, female. Borneo. (After Westwood.)
The prothorax is elongate, but there are a few genera, e.g. Eremiaphila, in which it is exceptionally short, and there are several others in which the elongate form is more or less masked by foliaceous expansions of the sides. The pronotum shows near the front a transverse depression or seam, which marks the position of an internal chitinous ridge. The anterior legs are inserted near the front of the prosternum, which extends less far forwards than the pronotum does; the posterior part of the prosternum is very elongate, and is completely separated from the anterior part by the base of the coxae and the membranes attached to them; the pronotum and sternum are closely connected at the sides till near the posterior part where they diverge, the space so formed being occupied by a membrane in which the prothoracic stigma is situated. The mesothorax is as long as broad, and the front wings are attached to the whole length of the sides; the mesosternum is a triangular piece pointed behind, and bearing very large side-pieces, to the hinder portion of which the middle coxae are attached; these latter are large and quite free, and repose on the metasternum which they cover; the mesothoracic stigma may be detected as a slit situated on a slight prominence just behind and a little below the membranous hind-margin of the tegmen. The metathorax differs comparatively little in size and structure from the mesothorax; the membranous hind wings are attached to the sides of the notum along nearly the whole length of the latter. The abdomen is moderately long; in each sex ten dorsal plates may be detected, and there is a pair of ringed cerci projecting from beneath the sides of the tenth plate. The number of ventral plates is more difficult to verify, the first one being much reduced; eight other plates can be demonstrated in the male and six in the female.
Fig. 136.—Head of Harpax variegatus, seen from the front.
The anterior legs are formed in a remarkable manner in the Mantidae, and are, in fact, the most characteristic feature of the family. Attached near the front of the thorax there is a very long coxa, to the apex of which is articulated the triangular trochanter; this bears the elongate femur, which is furnished on its lower face with sharp spines and teeth; the tibia which follows is much shorter and smaller than the femur; its lower face bears also an armature of teeth, and it is so articulated with the femur that it can be completely closed thereon, its teeth fitting in among those of the femur (Fig. 137, B); the latter has one or more longer spines overlapping the apical part of the tibia when contracted. The tarsus is slender, five-jointed, without pad. The other two pairs of legs are simple; the hinder usually a little the longer, and in some species that possess powers of leaping (Ameles), with the femora a little thicker at the base.
Fig. 137.—Front leg of Empusa pauperata, female: A, with tibia extended and tarsus wanting; B, more magnified (the basal parts removed), showing the mode of closure.