Marching and Harvesting Termites.—Smeathman alluded to a remarkable Termes seen by him in Africa, giving it the name of T. viarum. Nothing further is known of this Insect, which, according to Smeathman's account, may possibly be the most remarkable of the family. T. viarum is said to be larger than T. bellicosus, and was discovered issuing in large numbers from a hole in the ground and marching in columns consisting of workers directed by soldiers of enormous size, some of whom climbed up plants and gave audible signals to the army, which immediately responded with a hissing noise and by increasing their pace with the utmost hurry; they continued marching by the spot where Smeathman observed them for upwards of an hour. He was not able to find their nests, and no specimens have been preserved; both soldiers and workers possessed eyes. Marching in this way by daylight is contrary to the nature of ordinary Termites, and some doubt has existed as to the correctness of Smeathman's observation, which has in fact remained for upwards of a century without confirmation.
Fig. 238.—Eyed, grass-cutting Termite, Hodotermes havilandi, A, soldier; B, worker. South Africa. In life the head is carried horizontally, so the piece of grass sticks up like a flag-pole.
Mr. G. D. Haviland has, however, this year discovered in Natal a Termite which shows that there are species in Africa of the kind described by Smeathman, the workers and soldiers being possessed of facetted eyes. Mr. Haviland states that the workers of this species issue from holes in the ground during the heat of the day and cut grass both dead and green. They carry it, in lengths of about two inches, to the mouths of the holes, often leaving it there and going at once to fetch more. Under acacia bushes they carry acacia leaflets as well as grass. In the middle of the day more grass accumulates at the entrance to the holes than can be taken in, but as the heat of the day diminishes the workers cease to forage and take in the accumulation. When the grass is all in they sometimes close the mouth of the hole with moistened pellets of earth brought in their mouths. The soldiers remain in the holes; when disturbed they jerk themselves like soldiers of other species to frighten away the intruder; when they bite, their grip is very tenacious. The holes are about ⅓ of an inch in diameter, and there are usually several of them a few yards apart; around each of them is a patch over which the grass has been cut quite short. Mr. Haviland followed these holes by digging for a distance of 20 feet and to a depth of 5½ feet; they remain uniform in size except that near the entrance there may be one or two chambers in which the grass is temporarily stored, but these do not hold more than would be collected in an hour or two. As the burrow descends it is occasionally joined by another, and at the point of junction there is usually a considerable widening. Sometimes they run straight for 6 or 7 feet, sometimes they curve abruptly, sometimes they are nearly horizontal, but near the mouth may be almost vertical in direction. These Termites are very local, but the specimens are numerous when found. Mr. Haviland dug for these Insects at two places on the Tugela river, one of them being at Colenso. It is much to be regretted that he was unable to reach the nest. We figure a soldier selected from specimens sent by Mr. Haviland to the Cambridge University Museum. This Insect is apparently much smaller than Smeathman's T. viarum. Other species of Termitidae have been described[[301]] as forming underground tunnels in Africa, but none of the species have yet been satisfactorily identified.
It was stated by Smeathman that some species of Termites had chambers in their habitations in which grew a kind of fungus used by the Insects for food; Mr. Haviland is able to confirm Smeathman in this particular; he having found fungus-chambers in the nests of more than one species both in Singapore and South Africa (Fig. 240).
Habitations.—In nothing do Termites differ more than in the habitations they form. Sometimes, as we have mentioned in the case of Calotermes, there is no real structure formed; only a few barriers being erected in burrows or natural hollows in wood. In other cases very extensive structures are formed, so that the work of the Termites becomes a conspicuous feature in the landscape. This is of course only the case in regions that are not much interfered with by man; the great dwellings spoken of by Smeathman and others soon disappear from the neighbourhood of settlements, but in parts of Africa and in Australia large dwellings are still formed by these creatures. In the latter part of the world there exists a very remarkable one, formed by an undetermined species called by the officers and crew of her Majesty's ship Penguin the "compass ant." The outline of one of the structures formed by this Termite we represent in Fig. 239. Mr. J. J. Walker, to whom we are indebted for the sketch from which this figure is taken, has also favoured us with the following extract from his diary, of date 4th August 1890: "The most interesting feature in the scenery (about forty miles inland from Port Darwin) was the constant succession of huge mounds raised by the Termites, of which I had seen some comparatively small examples in my rambles near Port Darwin; but these exceeded in dimensions all I had ever seen. The most frequent as well as the largest kind was usually of a reddish or ferruginous colour outside, and generally almost cylindrical in shape with obtusely-pointed top, but nearly always more or less weather-worn, with great irregular buttresses and deep ruts down the sides; many of them look like ruined towers in miniature. Their usual height was from 8 to 10 feet, but many were much higher, and some attained an (estimated) elevation of at least 20 feet. Another kind, seen only in one or two places along the line, was of a much more singular character; they averaged only 4 to 5 feet high, were built of a dark-gray mud, and in shape were like thin flat wedges set upright (see Fig. 239), reminding one of tombstones in a churchyard. But the most remarkable feature about these mounds was that they had all the same orientation, viz. with the long faces of the wedge pointing nearly north and south. Why this is so I am quite at a loss to imagine, and I much regret that I had no opportunity of closely examining these most singular structures. A third kind of mound, usually not exceeding 2 feet in height, was of a simple, acute, conical figure, and generally of a gray colour somewhat paler than the last."
Fig. 239.—Termitarium of compass or meridian Termite of North Australia. A, face extending south and north; B, cross-section.
The material used for the construction of the dwellings is either earth, wood, or the excrement of the Termites. The huge edifices mentioned by Smeathman are composed of earth cemented together so as to look like stone or brick, and the buildings appear to be almost as strong as if they were actually constructed with these materials. In many cases the substance used is comminuted wood that has passed one or more times through the alimentary canal of the Insects, and may therefore be called excrement. Whether the stone-like material is made from earth that has passed through the alimentary canal or from grains gathered for the purpose has not been well ascertained. In any case the material is cemented together by means of the secretions of glands. Dudley and Beaumont have described the process of construction, in a species observed by them, saying that earth is brought and placed in position by the mandibles, and cemented by liquid from the abdomen.[[302]] Von Jhering says[[303]] that some species form the exterior walls of their dwellings of stone-like material, but make use of woody matter for the construction of the interior. Smeathman has described the nest of Termes bellicosus. The whole of the very strong external wall consists of clay-like material, cemented by the secretions of the Termites to a very firm consistence. The royal cell is built of the same material as the framework of the nest; whilst the nurseries in which the young are chiefly found are built of woody material, and are always covered with a kind of mould—the mycelium of a fungus—and plentifully sprinkled with small white bodies, which, under the microscope, are found to be filled with a number of oblong, spore-like cells.
