Fig. 178.—Cephalocoema lineata, female, × ⅔. S. America. (After Brunner.)
In Britain we are now exempt from the ravages of locusts, though swarms are said to have visited England in 1693 and 1748. Individuals of the migratory species are, however, still occasionally met with in England and the south of Scotland. P. cinerascens has been recorded from Kerry in Ireland, but erroneously, the Insect found being Mecostethus grossus (Fig. 173). According to Miss Ormerod,[[233]] large locusts are imported to this country in fodder in considerable numbers, but are usually dead; living individuals are, however, sometimes found among the others. In 1869 living specimens of Schistocerca peregrina were found in various parts of the country, having, in all probability, arrived here by crossing the German Ocean. Pachytylus cinerascens has also, it is believed, occurred here, the specimens that have been recorded at different times under the name of P. migratorius being more probably the former species.
Although the majority of the very large number of species included in Acridiidae are recognised with ease from their family likeness as belonging to the group, yet there are others that present an unusual aspect. This is specially the case with the members of the small tribes Tettigides, Proscopides, and Pneumorides, and with some of the apterous forms of the Oedipodides. The tribe Proscopides (Fig. 178, Cephalocoema lineata, female) includes some of the most curious of the Acridiidae. Breitenbach gives[[234]] a brief account of the habits of certain species which he met with near Porto Alegre in South America. On a stony hill there was some grass which, by several months' exposure to the sun's rays, had become withered and brown. Apparently no live thing was to seen on this hillock except the ubiquitous ants, but after a while he noticed some "lightning-like" movements, which he found were due to specimens of Proscopia. The Insects exactly resemble the withered vegetation amongst which they sit, and when alarmed seek safety with a lengthy and most rapid leap. When attention was thus directed to them he found the Insects were really abundant, and was often able to secure fifty specimens on a single afternoon. These Insects bear a great general resemblance to the Phasmides, but there is no evidence at present to show that the two kinds of Insects live in company, as is the case with so many of the Insects that resemble one another in appearance. Although the linear form and the elongation of the body are common to the stick-Insects and the Proscopides, yet this structure is due to the growth of different parts in the two families. In the Phasmidae the prothorax is small, the mesothorax elongate, while in the Proscopides the reverse is the case. The elongation of the head is very curious in these Insects; the mouth is not thus brought any nearer to the front, but is placed on the under side of the head, quite close to the thorax. The tribe Tryxalides contains Insects (Fig. 165) that approach the Proscopides in the form of the head and other characters. In most cases the sexes of the Proscopides differ from one another so strongly that it is difficult to recognise them as being of the same species. Usually both sexes are entirely apterous, but the Chilian genus Astroma exhibits a remarkable exception and an almost unique condition of the alar organs, the mesonotum being in each sex entirely destitute of such appendages, while the female has on the metanotum rudiments of wings which are absent in the male.
Fig. 179.—Tettix bipunctatus. Britain. A, The Insect magnified; B, part of the middle of the body; a, prolongation of pronotum; b, tegmen; c, wing.
The tribe Tettigides is a very extensive group of small Acridiidae, in which the pronotum extends backwards as a hood and covers the body, the tegmina and wings being more or less modified. In our British species (Fig. 179) this condition does not greatly modify the appearance of the Insect, but in many exotic species (Fig. 180) the hood assumes remarkable developments, so that the Insects have no longer the appearance of Orthoptera. It would be impossible, without the aid of many figures, to give an idea of the variety of forms assumed by this prothoracic expansion. It is a repetition of what occurs in the Order Hemiptera, where the prothoracic hoods of the Membracides exhibit a similar, though even more extraordinary, series of monstrous forms. So great is the general similarity of the two groups that when the genus Xerophyllum (Fig. 180, A) was for the first time described, it was treated by the describer as being a bug instead of a grasshopper. This genus includes several species from Africa. The curious Cladonotus (Fig. 180, B) is a native of Ceylon, where it is said to live in sandy meadows, after the fashion of our indigenous species of Tettix (Fig. 179). Very little is known as to the habits of these curious Tettigides, but it has been ascertained that some of the genus Scelimena are amphibious, and do not hesitate to enter the water and swim about there; indeed it is said that they prefer plants growing under water as food. This habit has been observed both in Ceylon and the Himalayas. The species are said to have the hind legs provided with dilated foliaceous appendages useful for swimming.
Fig. 180.—Tettigides: A, Xerophyllum simile Fairm.; B, Cladonotus humbertianus. (After Bolivar.)
