Fig. 140.—Iris oratoria, female. South Europe. Natural size.
The Mantidae, as a rule, have a quiet unobtrusive mien, and were it not for their formidable front legs would look the picture of innocence; they, however, hold these legs in such manner as to greatly detract from the forbidding appearance thereof, stretching them out only partially so as to give rise to an appearance of supplication or prayer;[[175]] this effect is increased by their holding themselves in a semi-erect position, standing on the hind and middle legs with the upper parts of the body directed somewhat forwards, hence they are called by various names indicating prayer or supplication, and it is said that in some countries they are considered sacred. Some of the older writers went so far as to say that a Mantis would indicate the road a child should take by stretching out one of its arms in the right direction. The traveller Burchell, speaking of a species since described by Westwood under the name of Tarachodes lucubrans, says: "I have become acquainted with a new species of Mantis, whose presence became afterwards sufficiently familiar to me by its never failing, on calm warm evenings, to pay me a visit as I was writing my journal, and sometimes to interrupt my lucubrations by putting out the lamp. All the Mantis tribe are very remarkable Insects; and this one, whose dusky sober colouring well suits the obscurity of night, is certainly so, by the very late hours it keeps. It often settled on my book, or on the press where I was writing, and remained still, as if considering some affair of importance, with an appearance of intelligence which had a wonderful effect in withholding my hand from doing it harm. Although hundreds have flown within my power, I never took more than five. I have given to this curious little creature the name of Mantis lucubrans; and having no doubt that he will introduce himself to every traveller who comes into this country [Southern Africa] in the months of November and December, I beg to recommend him as a harmless little companion, and entreat that kindness and mercy may be shown to him." This appearance of innocence and quietness must have struck all who have seen these Insects alive; nevertheless, it is of the most deceptive character, for the creature's activity consists of a series of wholesale massacres carried on day after day, the number of victims it sacrifices being enormous. The Mantis does not even spare its own kind; it is well known that the female not unfrequently devours its own mate. A very different picture to that of Burchell has been drawn by Potts, who observed the habits of a species in New Zealand.[[176]] He informs us that when about making an attack it approaches its intended prey with slow, deliberate movements, its anterior limbs folded in an innocent fashion, now and then raising itself or lifting the prothorax in a stealthy quiet manner, perhaps to judge accurately of its distance; when near enough, with one swift dart the victim is secured. The prey is held firmly in the formidable trap formed by the anterior leg, and is thus brought near the mouth. The Mantis usually commences its feast by taking off some portions of the head of its wretched victim, and displays an absolute indifference to its struggling or kicking; the mandibles having seized a portion of the food, the legs holding it move away, thus leaving a fragment in the mouth. Portions only of a captured Insect are consumed, much being cast away; and Mr. Potts states that he has seen one of these voracious creatures kill and devour parts of fourteen small flies within a very brief space of time. This voracity and waste of animal food is very remarkable when we recollect that many Insects have such perfect powers of assimilation that during their whole period of growth they only consume a mass of food—and that vegetable—but little larger in size than the bulk they themselves attain. This fact is well known in the case of Bruchus, Caryoborus, and other seed-feeding Insects. Burmeister has stated good grounds for believing that some of the larger Mantidae do not confine themselves to Insect diet, but attack and devour small Vertebrates.[[177]] He has given a circumstantial account of a case at Buenos Ayres, where a small bird was secured by the wingless female of a large Mantis, which had commenced devouring its head when the observer took possession of the creature and its booty. Dubois states[[178]] that when a decapitated, but living, Mantis was suspending itself to a roll of drapery by its four posterior legs, a person could detach with the fingers the left anterior leg (of the four) and the right posterior, or conversely the left posterior and right anterior, without the interference producing any action on the part of the creature; but if one of the other legs was also interfered with, which would necessarily have changed the position of the body, then immediately one of the two unoccupied legs was placed by the creature in a proper position to assure its stability. This reflex action altogether resembled in appearance a conscious action, and was as effectually performed.
The combination in Mantidae of voracious and destructive instincts with helpless and inert attitudes gives rise to the idea that these latter are adopted for the purpose of deceiving the living prey and of thus more easily obtaining the means of subsistence. It appears, however, more probable that the helpless attitudes have no such origin, but are due to the structure and form of the creature. The front legs being wonderfully well formed for raptorial purposes, have no capacity for locomotion or for supporting the Insect in the usual manner, so that the body has to be borne by the hinder two pairs of legs; at the same time the raptorial pair of limbs—which, it will be recollected, are of great size and attached to the anterior part of an unusually long prothorax—have to be held in such a position as will not derange the equilibrium maintained by the posterior part of the body; moreover, these large raptorial legs are entirely exserted, and have no trace of any articulatory cavity that might act as a mechanical aid to their support. Thus they could not be held extended without great muscular exhaustion; hence we can well believe that the sedentary and helpless attitudes of the creature are not the results of any guile.
A Mantis has been recorded as bearing a close resemblance to a Phasmid of the genus Bacillus and having only small front legs; it was suggested by Bates[[179]] that the Mantis would probably be found to feed on the Bacillus. Though the case is of considerable interest, no further information about it has been obtained.
Fig. 141.—Mantoida luteola Westw., male. Santarem.
The simplest forms of the family are found in the groups Amorphoscelides and Orthoderides. From our figure of one of these (Fig. 141, Mantoida luteola ♂), it will be seen that the peculiarities of the family can scarcely be detected, the raptorial legs being very little developed and the prothorax short. The sexes, too, differ but little in these simple forms. Most of them are very rare in collections, but Wood-Mason states[[180]] that Amorphoscelis annulicornis is frequently found about Calcutta on the trunks of trees, to the bark of which it is so similar that it is only discovered with difficulty. In its rapid movements it resembles the cockroaches or Machilis, more than it does the more differentiated forms of its own group.
In the genus Pyrgomantis (Fig. 142, P. singularis, female) the male has the tegmina and wings of normal size, while in the female they are rudimentary.
Fig. 142.—Pyrgomantis singularis, female. S. Africa. (After Westwood.)