NEUROPTERA. Dragon-flies.—Of the Neuroptera, some of the dragon-flies are pre-eminently beautiful; one species, with rich brown-coloured spots upon its gauzy wings, is to be seen near every pool.[4111] Another[4112], which dances above the mountain streams in Oovah, and amongst the hills descending towards Kandy, gleams in the sun as if each of its green enamelled wings had been sliced from an emerald.
The Ant-Lion.—Of the ant-lion, whose larvæ have earned a bad renown from their predaceous ingenuity, Ceylon has, at least, four species, which seem peculiar to the island.[4113] This singular creature, preparatory to its pupal transformation, contrives to excavate a conical pitfall in the dust to the depth of about an inch, in the bottom of which it conceals itself, exposing only its open mandibles above the surface; and here every ant and soft-bodied insect which curiosity tempts to descend, or accident may precipitate into the trap, is ruthlessly seized and devoured by its ambushed inhabitant.
The White Ant.—But of the insects of this order the most noted are the white ants or termites (which are ants only by a misnomer). They are, unfortunately, at once ubiquitous and innumerable in every spot where the climate is not too chilly, or the soil too sandy, for them to construct their domed edifices.
These they raise from a considerable depth under ground, excavating the clay with their mandibles, and moistening it with tenacious saliva[4121] until it assume the appearance, and almost the consistency, of sandstone. So delicate is the trituration to which they subject this material, that the goldsmiths of Ceylon employ the powdered clay of the ant hills in preference to all other substances in the preparation of crucibles and moulds for their finer castings: and KNOX says, "the people use this finer clay to make their earthen gods of, it is so pure and fine."[4122] These structures the termites erect with such perseverance and durability that they frequently rise to the height of ten or twelve feet from the ground, with a corresponding diameter. They are so firm in their texture that the weight of a horse makes no apparent indentation on their solidity; and even the intense rains of the monsoon, which no cement or mortar can long resist, fail to penetrate the surface or substance of an ant hill.[4131] In their earlier stages the termites proceed with such energetic rapidity, that I have seen a pinnacle of moist clay, six inches in height and twice as large in diameter, constructed underneath a table between sitting down to dinner and the removal of the cloth.
As these lofty mounds of earth have all been carried up from beneath the surface, a cave of corresponding dimensions is necessarily scooped out below, and here, under the multitude of miniature cupolas and pinnacles which canopy it above, the termites hollow out the royal chamber for their queen, with spacious nurseries surrounding it on all sides; and all are connected by arched galleries, long passages, and doorways of the most intricate and elaborate construction. In the centre and underneath the spacious dome is the recess for the queen—a hideous creature, with the head and thorax of an ordinary termite, but a body swollen to a hundred times its usual and proportionate bulk, and presenting the appearance of a mass of shapeless pulp. From this great progenitrix proceed the myriads that people the subterranean hive, consisting, like the communities of the genuine ants, of labourers and soldiers, which are destined never to acquire a fuller development than that of larvæ, and the perfect insects which in due time become invested with wings and take their departing flight from the cave. But their new equipment seems only destined to facilitate their dispersion from the parent nest, which takes place at dusk; and almost as quickly as they leave it they divest themselves of their ineffectual wings, waving them impatiently and twisting them in every direction till they become detached and drop off, and the swarm, within a few hours of their emancipation, become a prey to the night-jars and bats, which are instantly attracted to them as they issue in a cloud from the ground. I am not prepared to say that the other insectivorous birds would not gladly make a meal of the termites, but, seeing that in Ceylon their numbers are chiefly kept in check by the crepuscular birds, it is observable, at least as a coincidence, that the dispersion of the swarm generally takes place at twilight. Those that escape the caprimulgi fall a prey to the crows, on the morning succeeding their flight.
The strange peculiarity of the omnivorous ravages of the white ants is that they shrink from the light; in all their expeditions for providing food they construct a covered pathway of moistened clay, and their galleries above ground extend to an incredible distance from the central nest. No timber, except ebony and ironwood, which are too hard, and those which are strongly impregnated with camphor or aromatic oils, which they dislike, presents any obstacle to their ingress. I have had a case of wine filled, in the course of two days, with almost solid clay, and only discovered the presence of the white ants by the escape from the corks. I have had a portmanteau in my tent so peopled with them in the course of a single night that the contents were found worthless in the morning. In an incredibly short time a detachment of these pests will destroy a press full of records, reducing the paper to fragments; and a shelf of books will be tunnelled into a gallery if it happen to be in their line of march. The timbers of a house when fairly attacked are eaten from within till the beams are reduced to an absolute shell, so thin that it may be punched through with the point of the finger: and even kyanized wood, unless impregnated with an extra quantity of corrosive sublimate, appears to occasion them no inconvenience. The only effectual precaution for the protection of furniture is incessant vigilance—the constant watching of every article, and its daily removal from place to place, in order to baffle their assaults.
They do not appear in the hills above the elevation of 4000 or 5000 feet. One species of white ant, the Termes Taprobanes, was at one time believed by Mr. Walker to be peculiar to the island, but it has recently been found in Sumatra and Borneo, and in some parts of Hindustan.
There is a species of Termes in Ceylon (T. monoceros), which always builds its nest in the hollow of an old tree; and, unlike the others, carries on its labours without the secrecy and protection of a covered way. A marching column of these creatures may be observed at early morning in the vicinity of their nest, returning laden with the spoils collected during their foraging excursions. These consist of comminuted vegetable matter, derived, it may be, from a thatched roof, if one happens to be within reach, or from the decaying leaves of a coco-nut. Each little worker in the column carries its tiny load in its jaws; and the number of individuals in one of these lines of march must be immense, for the column is generally about two inches in width, and very densely crowded. One was measured which had most likely been in motion for hours, moving in the direction of the nest, and was found to be upwards of sixty paces in length. If attention be directed to the mass in motion, it will be observed that flanking it on each side throughout its whole length are stationed a number of horned soldier termites, whose duty it is to protect the labourers, and to give notice of any danger threatening them. This latter duty they perform by a peculiar quivering motion of the whole body, which is rapidly communicated from one to the other for a considerable distance: a portion of the column is then thrown into confusion for a short time, but confidence soon returns, and the progress of the little creatures goes on with steadiness and order as before. The nest is of a black colour, and resembles a mass of scoriæ; the insects themselves are of a pitchy brown.[4161]
HYMENOPTERA. Mason Wasp.—In Ceylon as in all other countries, the order of hymenopterous insects arrests us less by the beauty of their forms than the marvels of their sagacity and the achievements of their instinct. A fossorial wasp of the family of Sphegidæ,[4171] which is distinguished by its metallic lustre, enters by the open windows, and converts irritation at its movements into admiration of the graceful industry with which it stops up the keyholes and similar apertures with clay in order to build in them a cell. Into this it thrusts the pupa of some other insect, within whose body it has previously introduced its own eggs. The whole is surrounded with moistened earth, through which the young parasite, after undergoing its transformations, gnaws its way into light, to emerge as a four-winged fly.[4172]
A formidable species (Sphex ferruginea of St. Fargeau), which is common to India and most of the eastern islands, is regarded with the utmost dread by the unclad natives, who fly precipitately on finding themselves in the vicinity[4181] of its nests. These are of such ample dimensions, that when suspended from a branch, they often measure upwards of six feet in length.[4182]