Pertinacity is one of the most curious features of the performance of musical Locustids. One would say they desire to distinguish themselves as much as possible. Harris says that Cyrtophyllus concavus mounts on the uppermost twigs of trees and there performs its Katy-did-she-did in rivalry with others. He says even the female in this species gives forth a feeble noise. Scudder says that some of the Katydids sing both by day and night, but their day song differs from that of the night. "On a summer's day it is curious to observe these little creatures suddenly changing from the day to the night song at the mere passing of a cloud, and returning to the old note when the sky is clear. By imitating the two songs in the daytime the grasshoppers can be made to respond to either at will; at night they have but one note."
Although but little is known as to the habits of Locustidae, it is ascertained that they are less exclusively herbivorous in their food habits than the Acridiidae are; many seem to prefer a mixed diet. Locusta viridissima will eat various leaves and fruits, besides small quantities of flesh. It has been recorded that a specimen in confinement mastered a humble-bee, extracted with its mandibles the honey-bag, and ate this dainty, leaving the other parts of the bee untouched. Many of the Locustidae are believed to be entirely carnivorous. Brunner considers a minority to be exclusively phytophagous. The species very rarely increase to large numbers; this, however, occurs sometimes with Orphania denticauda and Barbitistes yersini in Europe, and Anabrus purpurascens in North America. We have already mentioned that the eggs of some species are deposited in parts of plants, and of others in the earth. The British Meconema varium deposits its eggs in the galls of Cynips in the autumn; these eggs do not hatch till the following spring. Xiphidium ensiferum has somewhat similar habits in North America, the gall selected for the reception of the eggs being the scales formed by a species of Cecidomyia on the leaves of willows. It has been ascertained that the development of the embryo in the last-named species is commenced in the autumn, but is suspended during the winter, being only completed in the following spring, eight or nine months afterwards. We owe to Wheeler[[250]] a memoir on the embryology of this Insect.
Some of the species have the peculiar habit of dwelling in caves. This is especially the case with the members of the tribe Stenopelmatides (Fig. 197), which frequently possess enormously long antennae and legs, and are destitute of alar organs and ears. The species with this habit, though found in the most widely separated parts of the world, have a great general resemblance, so that one would almost suppose the specimens found in the caves of Austria, in the Mammoth cave of Kentucky, and in the rock-cavities of New Zealand to be one species, although they are now referred by entomologists to different genera.
Fig. 197.—Dolichopoda palpata, male. Dalmatia. (After Brunner.)
Fig. 198.—Leaf-like tegmen of Pterochroza ocellata: a, a, a, marks like those made by Insects on leaves.
The Locustidae display in the greatest possible perfection that resemblance of the tegmina to leaves which we mentioned when speaking of the general characters of the Orthoptera. The wing-covers are very leaf-like in colour and appearance in many Locustidae, but it is in the tribe Pseudophyllides and in the South American genus Pterochroza (Fig. 198) that the phenomenon is most remarkable. The tegmina in the species of this genus look exactly like leaves in certain stages of ripeness or decay. In the tegmina of some of the species not only are the colours of faded leaves exactly reproduced, but spots are present like those on leaves due to cryptogamic growths. Perhaps the most remarkable feature of these resemblances is the one pointed out by Brunner von Wattenwyl,[[251]] viz. that the tracks and spots formed on leaves by the mining of Insects in their tissues are also represented in the leaf-like wing-covers of the Pterochroza; transparent spots (a, a, Fig. 198) being present, just as they are in many leaves that have been attacked by Insects. Brunner was so much impressed by these facts that he came to the conclusion that they cannot be accounted for on the grounds of mere utility, and proposed the term Hypertely to express the idea that in these cases the bounds of the useful are transcended. We will mention here another peculiar case of resemblance described by Brunner as occurring in a Locustid. Two specimens of a little Phaneropterid were brought from the Soudan by the Antinori expedition, and have been described by Brunner under the name of Myrmecophana fallax. The Insect is said to bear an extraordinary resemblance to an ant. The most peculiar feature in the resemblance is shown in Fig. 199, A, B. The most characteristic point in the external form of an ant is the stalked abdomen, this structure being at the same time quite foreign to the Orthoptera. In the other parts of the body and in the colour generally, the Myrmecophana resembles an ant, but the abdomen of the Orthopteron is not stalked; it has, however, the appearance of being so, in consequence of certain parts being of a white colour, as shown in our figure. If abstraction be made of the white parts, the form of the stalked abdomen of the ant is nicely reproduced. The specimens brought from the Soudan were wingless and destitute of ovipositor, and may be immature, but Brunner suggests that they may prove to be really mature, the ovipositor, tegmina, and wings being permanently absent. The existence of a long ovipositor would certainly detract greatly from the ant-like appearance of the Orthopteron.
Fig. 199.—Myrmecophana fallax.