Head prolonged to form a deflexed beak, provided with palpi near its apex; wings elongate and narrow, shining and destitute of hair, with numerous, slightly divergent veins and moderately numerous transverse veinlets (in one genus the wings are absent). Larvae provided with legs, and usually with numerous prolegs like the saw-flies: habits carnivorous.
Fig. 294.—Panorpa communis, male. Cambridge.
The majority of the members of this family are very readily distinguished by the beak-like front of the head, this being chiefly due to enlargement of parts of the head itself, and in a less degree to prolongation of the mouth-parts. The upper (or front) face of the beak is formed entirely by the clypeus, the labrum being scarcely visible, though it may be detected at the sides of the tip of the beak; the sutures between the various parts of the head are nearly or quite obliterated, but it is probable that the sides of the beak are formed by the genae and by the stipites of the maxillae, and its under-surface chiefly by the submentum: the mentum itself is but small, the ligula is small, bifid at the extremity, and each branch bears a two-jointed palpus, the basal article being of very peculiar structure in Panorpa. The mandibles are but small, and are placed at the apex of the beak; they have each the form of an oblong plate armed with two very sharp teeth, and they cross freely. The maxillae are the only parts of the mouth-pieces that are very elongated; each cardo is articulated at the base of the head, and the stipes extends all the length of the side of the beak; each maxilla bears a five-jointed palpus and two small but very densely ciliated lobes. The antennae are long, very slender, and flexible, and are many-jointed; they are inserted between the eyes in large foramina; there are three ocelli, or none, and the compound eyes are moderately large. The prothorax is small, its notum is quite small or moderate in size, and the prothoracic stigma is placed behind it; the side-pieces are small, and there is no chitinous prosternum except a small longitudinal strip placed in the membrane between the coxae; these latter are of only moderate size, and are free and dependent. The meso- and meta-thorax are large, their side-pieces are of considerable dimensions and bear large, dependent coxae and supporting-pieces (Fig. 58); there is a stigma placed between the meso- and meta-thorax at the hind margin of the upper part of the meso-trochantin; both meso- and meta-notum are transversely divided. The abdomen is elongate, slender, conico-cylindrical, consisting of nine segments; the basal segment is membranous and concealed; the terminal appendages are of variable nature according to the species and sex. The legs are elongate and slender, the tarsi five-jointed. The internal anatomy of Panorpa communis has been examined by Dufour[[377]] and Loew.[[378]] They agree in describing the alimentary canal as being of peculiar structure: there is a short, slender oesophagus leading to an organ in which there is seated a remarkable arrangement of elongate hairs; this structure might be looked on as the proventriculus, but Loew considers it to be rather a division of the true stomach. The particulars given by these two anatomists as to some other parts of the internal anatomy are very discrepant.
The Panorpidae form a small family of only nine or ten genera, two or three of these being exotic and only imperfectly known; the three genera found in Europe are composed of very curious Insects. The scorpion-flies—Panorpa proper—are very common Insects, and have received their vernacular name from the fact that the males have the terminal segments elongate and slender and very mobile, and carry them curved up somewhat after the fashion of the scorpions (Fig. 294). It is said that Aristotle was acquainted with these Insects, and considered them to be really winged scorpions.
A second European genus, Boreus, is still more peculiar; it is destitute of wings, and has the appearance of a minute wingless grasshopper; it is found from late autumn to early spring in moss and under stones, and is said to be sometimes found disporting itself on the surface of the snow: the female of this Insect has an exserted ovipositor. The writer has found this little creature in Scotland among moss in November, and under stones early in March (Fig. 295). The third European genus, Bittacus, does not occur in our islands, but is common on many parts of the Continent; the perfect Insect has a great resemblance to a Tipula, or "daddy-long-legs" fly, and attaches itself to the stems of grasses, and preys on flies; according to Brauer it has the peculiar habit of using the hind pair of legs as hands (Fig. 296), instead of the front pair, as is usual in Insects. This remarkable genus is widely distributed, and species of it are found even in the Antipodes. A species inhabiting caves has been mentioned by M‘Lachlan.[[379]]
Fig. 295.—Boreus hiemalis, female. Dumfriesshire.
The early stages of the Panorpidae were for long unknown, but have recently been discovered by Brauer: he obtained eggs of Panorpa by confining a number of the perfect flies in a vessel containing some damp earth on which was placed a piece of meat; when the young larvae were hatched they buried themselves in the earth and nourished themselves with the meat or its juices.
