TROPICAL INSECTS, SPIDERS, AND SCORPIONS.
Gradual increase of Insect Life on advancing towards the Line—The Hercules Beetle—The Goliath—The Inca Beetle—The Walking-leaf, and Walking-stick Insects—The Soothsayer—Luminous Beetles—Tropical Spiders—Their gaudy colours—Trap-door Spiders—Enemies of the Spiders—Mortal Combat between a Spider and a Cockroach—Tropical Scorpions—Dreadful effects of their sting.
On advancing from the temperate regions to the line, we find the insects gradually increasing with the multiplicity of plants, and at length attaining the greatest size, brilliancy of colour, and variety of form in those tropical lands where moisture combines with heat in covering the ground with a dense and everlasting vegetation. Our largest insects are indeed mere pygmies when compared with their tropical relatives. We have no tiger-beetle to equal the ferocious Mantichora of South Africa, which, hiding beneath stones from the terrible glare of the sun, darts quickly from its place of concealment upon its ill-fated prey; nor a stag-beetle of the size of the Odontolabris Cuvera of China and Northern India. Our largest dung-feeding Lamellicorns look but small near the African Copris Hamadryas; and our cockchafer, though conspicuous among our native insects, is a dwarf when confronted206 with the Leucopholis bimaculata of India, which, if it be voracious in proportion to its size, must destroy a vast amount of vegetation in the course of its long larval existence. The Goliath beetles of the coast of Guinea, are truly deserving of their name, and in torrid America the colossal Hercules beetle attains a length of five, or even six inches. Though but little is yet known of its economy, it most likely subsists upon putrescent wood, and evidently leads a tree life, like its relations—the Elephant, the Neptune, the Typhon, the Hector,207 and the Mars beetles—whose very names indicate that they are ‘first-rate liners’ in the insect world. All these beetles excavate burrows in the earth, where they conceal themselves during the day, or live in the decomposed trunks of trees, and are generally of a dark rich brown or chestnut colour. On the approach of night they run about the footpaths in woods, or fly around the trees to a great height with a loud humming noise. Resembling the large herbivorous quadrupeds by their comparative size and horn-like processes, they are still further like them in their harmless nature, and thus deserve in more than one respect to be called the elephants among the insect tribes.
ODONTOLABRIS CUVERA.
COPRIS HAMADRYAS.
LEUCOPHOLIS BIMACULATA.
Many of the tropical dragon-flies, grasshoppers, butterflies, and moths are of no less colossal dimensions in their several orders than the giants among the beetles. The Libellula lucretia, a South American dragon-fly, measures five inches and a half in length, and the cinnamon-eating Atlas-moth of Ceylon often reaches the dimensions of nearly a foot in the stretch of its superior wings. The names of many other species conspicuous by their size might be added; but these examples suffice to show the enormous proportions attained by insects in the warmer regions of the globe.
In the tropical zone, where the prodigality of life multiplies208 the enemies which every creature has to encounter, we may naturally expect to find the insects extremely well provided with both passive and active means of defence.
Many so closely resemble in colour the soil or object on which they are generally found, as to escape even the eye of a hungry enemy. The wings of several Brazilian moths appear like withered leaves that have been gnawed round their margins by insects; and when these moths are disturbed, instead of flying away, they fall upon the ground like the leaf which they resemble, so that it is difficult, if not impossible, on such occasions to know what they really are.
PHYLLIUM.
The illusion is still more complete when the likeness of form is joined to that of colour, as in the walking-leaf and walking-stick insects. Some, of an enormous length, look so exactly like slender dead twigs covered with bark, that their insect nature can only be discovered by mere accident—upon being handled they feign death, and their legs are often knobbed, like the withered buds of trees; some resemble living twigs, and are green; others such as are decayed, and are therefore coloured brown; the wings of many put on the resemblance of dry and crumpled leaves, while those of others are vivid green—in exact accordance with the plants they respectively inhabit. This highly remarkable family consists of the herbivorous Phasmas and Phylliums—the former of which have a thin twig-like shape, while the latter have an enlarged body—and of the carniverous Mantides, or soothsayers. As the Mantis is slow and without much muscular energy, and its organisation requires a large supply of food, Nature has disguised it under the form of a plant, the better to deceive its victims. Like a cat approaching a mouse, it moves almost imperceptibly along, and steals towards its prey, fearful of putting it to flight. When sufficiently near, the fore legs are suddenly darted out to their full length, and seize the doomed insect, which vainly endeavours to extricate itself; the formation of the fore leg enabling the tibia to be so closed on the sharp edge of the thigh as to amputate any slender substance brought within its209 grasp, and to make even an entomologist repent a too hasty seizure of his prize.
The Mantis, by the attitude it assumes when lurking for its prey or advancing upon it—which is done by the support of the four posterior legs only, whilst the head and prothorax are raised perpendicularly from the body, and the anterior legs are folded in front—greatly resembles a person praying. Hence, in France it is called Le Prêcheur, or Le Prie Dieu; the Turk says it points to Mecca; and several African tribes pay it religious observances. In reality, however, its ferocity is great, and the stronger preying on the weaker of their own species, unmercifully cut them to pieces.
MANTIS.
Within the space of a week, Professor Burmeister saw a Mantis devour daily some dozens of flies, and occasionally large grasshoppers and young frogs, consuming, now and then, lizards three times its own length, as well as many large fat caterpillars. Hence it may be judged what ravages these strangely-formed creatures must cause among all weaker beings which incautiously approach them, and that, far from being the saints, they are, in reality, the tigers of the insect world. Among the organic marvels of the innocent herbivorous Phylliums, their seed-like eggs must be mentioned; for the wonderful provision of Nature in giving the parents a plant-like form extends even to their progeny, in order to secure them from similar dangers. Though generally tropical, yet Van Diemen’s Land possesses a gigantic walking-stick, or Phasma, the body of which is eight inches long; and the Mantis religiosa is found all over Southern Europe.
The leaf-like form which renders the Phylliums one of the wonders of entomology, appears likewise in other insects. Thus, in the Diactor bilineatus, a native of Brazil, the hind legs have singular leaf-like appendages to their tibial joints; and in the Javanese Mormolyce, a beetle remarkable for its extreme flatness and the elongation of its head, we find the upper wings spreading out in the form of broad leaves.
The long hairs, stiff bristles, sharp spines, and hard tubercular prominences with which many caterpillars are bristled210 and studded, are a most effectual means of defence, and often prove a grievous annoyance to the entomologist, from their poisonous or stinging properties. Mr. Swainson once finding in Brazil a caterpillar of a beautiful black colour, with yellow radiated spines, and being anxious to secure the prize, incautiously took hold of it with the naked hand; but so instantaneous and so violent was the pain which followed, that he was obliged to return home. Every device that could be thought of to allay the itching produced by the venomous hairs of this creature were in turn resorted to, with little or no effect for several hours, nor had it entirely ceased on the following morning.
JAVANESE MORMOLYCE.
Though the great majority of luminous animals are marine, frequently lighting up the breaking wave with millions of moving atoms, or spreading over the beach like a sheet of fire,20 yet several insects are also endowed with the same wonderful property. The European glow-worms and fire-flies, sparkling on the hedge-rows, or flying in the summer air, afford a charming spectacle; but their brilliancy is far surpassed by that of the phosphorescent beetles of the torrid zone. Thus the Cocujas of South America, which emits its light from two little transparent tubercles on the sides of the thorax, glows with such intensity that a person may with great ease read the smallest print by the phosphorescence of one of these insects, if held between the fingers and gradually moved along the lines with the luminous spots above the letters; but if eight or ten of them are put into a phial the light will be sufficiently good to admit of writing by it.
COCUJAS.
The Indian Archipelago is equally rich in luminous insects. The Podada tree, the ornament of most of the river banks of Borneo, has a remarkably elegant foliage of a light green colour. Rajah Brooke21 describes these trees illuminated by the fire-flies211 in countless numbers as a most enchanting sight, and resembling a fire-work by the constant motion of the light. On the Samarahan he sometimes saw each side of the river lit by a blaze of these beautiful little insects.
In the woods of Sarawak Mr. Adams observed a splendid glow-worm (Lampyris), each segment of the body illuminated with three lines of tiny lamps, the luminous spots on the back being situated at the posterior part of the segmentary rings on the median line, while those along the sides of the animal were placed immediately below the stomates or spiracula, each spiraculum having one bright spot. This very beautiful insect was found shining as the darkness was coming on, crawling on the narrow pathway, and glowing among the dead damp wood and rotten leaves. When placed around the finger, it resembled in beauty and brilliancy a superb diamond ring.
The sparkling effulgence of the tropical Elaters is frequently made use of by the fair sex, as an equally singular and striking ornament. The ladies of the Havana attach them to their clothes on occasions of festivity, and the Indian dancing girls often wear them in their hair.
In Prescott’s ‘Conquest of Mexico’ we are told that, in 1520, when the Spaniards visited that country, the wandering sparks of the Elater, ‘seen in the darkness of the night, were converted by their excited imaginations into an army with matchlocks;’ and on another occasion these phosphorescent insects caused British troops to retreat: for when Sir John Cavendish and Sir Robert Dudley first landed in the West Indies, and saw at night an innumerable quantity of lights moving about, they fancied that the Spaniards were approaching with an overwhelming force, and hastily re-embarked before their imaginary foe.
A creature, half of whose body is generally fixed to the other by a mere thread, whose soft skin is unable to resist the least pressure, and whose limbs are so loosely attached to the body as to be torn off by the slightest degree of force, would seem utterly incapable of protecting its own life and securing that of its progeny. Such, however, is the physical condition of the spiders, who would long since have been extirpated if Nature had not provided them with the power of secreting two212 liquids, the one a venom ejected by their mandibles, the other of a glutinous nature, transuded by papillæ at the end of their abdomen. These two liquids amply supply the want of all other weapons of attack or defence, and enable them to hold their own against a host of enemies. With the former they instantly paralyse insects much stronger and much more formidable in appearance than themselves; while with the latter they spin those threads which serve them in so many ways—to weave their wonderful webs, to traverse the air, to mount vertically, to drop uninjured, to construct the hard cocoons intended to protect their eggs against their numberless enemies, or to produce the soft down which is to preserve them from the cold.
Preying on other insect tribes, which they attack with the ferocity of the tiger, or await in their snares with the patient artifice of the lynx, the spiders may naturally be expected to be most numerous in the torrid zone, where Nature has provided them with the greatest abundance and variety of food. There also, where so many beetles, flies, and moths attain a size unknown in temperate regions, we find the spiders growing to similar gigantic dimensions, and forming webs proportioned to the bulk of the victims which they are intended to ensnare.
In some parts of Makalolo, Dr. Livingstone saw great numbers of a large beautiful yellow-spotted spider, the webs of which were about a yard in diameter. The lines on which these webs were spun, extended from one tree to another, and were as thick as coarse thread. The fibres radiated from a central point, where the insect waited for its prey. The webs were placed perpendicularly, and a common occurrence in walking was to get the face enveloped in them, as a lady is in a veil.
By means of their monstrous webs many giant-spiders of the tropical zone are enabled to entangle not only the largest butterflies and moths, but even small birds. Some Mexican species extend such strong nets across the pathways, that they strike off the hat of the passer-by; in Senegal spiders spin threads so strong as to be able to bear a weight of several ounces, and in the forests of Java, Sir George Staunton saw spider-webs of so strong a texture that it required a sharp knife to cut one’s way through them; and many other similar examples might be mentioned.
213 These large spiders so temptingly suspended in mid-air in the forest glades, seem very much exposed to the attacks of birds, but in many cases it has pleased Nature to invest them with large angular spines sticking out of their bodies in every kind of fashion. Some are so protected by these long prickles that their bodies resemble a miniature ‘chevaux de frise,’ and could not by any possibility be swallowed by a bird without producing a very unpleasant sensation in his throat. One very remarkable species (Gasteracantha arcuata) has two enormous recurved conical spines, proceeding upwards from the posterior part of the body, and several times longer than the entire spider.
Other Araneæ, to whom these means of defence have been denied, are enabled by their colour to escape the attacks of many enemies, or to deceive the vigilance of many of their victims. Thus, those that spend their lives among the flowers and foliage of the trees are, in general, delicately and beautifully marked with green, orange, black, and yellow, while those which frequent gloomy places are clothed with a dark-coloured and dingy garb, in accordance with their habits. In the forests about Calderas, in the Philippine Archipelago, Mr. Adams saw handsomely coloured species of Theridia crouching among the foliage of the trees: while numbers of the same genus of a black colour were running actively about among the dry dead leaves that strewed the ground, looking, at a little distance, like odd-shaped ants, and no doubt deceiving many an antagonist by this appearance. One species, which knew it was being watched, placed itself upon a diseased leaf, where it remained quite stationary until after the departure of ............