The Naturalist on the River Amazons

Whenever a colony of Termites is disturbed, the workers are at first the only members of the community seen; these quickly disappear through the endless ramified galleries of which a Termitarium is

composed, and soldiers make their appearance. The observations of Smeathman on the soldiers of a species inhabiting tropical Africa are often quoted in books on Natural History, and give a very good idea of their habits. I was always amused at the pugnacity displayed, when, in making a hole in the earthy cemented archway of their covered roads, a host of these little fellows mounted the breach:to cover the retreat of the workers. The edges of the rupture bristled with their armed heads as the courageous warriors ranged themselves in compact line around them. They attacked fiercely any intruding object, and as fast as their front ranks were destroyed, others filled up their places. When the jaws closed in the flesh, they suffered themselves to be torn in pieces rather than loosen their hold. It might be said that this instinct is rather a cause of their ruin than a protection when a colony is attacked by the well-known enemy of Termites, the ant-bear; but it is the soldiers only which attach themselves to the long worm-like tongue of this animal, and the workers, on whom the prosperity of the young brood immediately depends, are left for the most part unharmed. I always found, on thrusting my finger into a mixed crowd of Termites, that the soldiers only fastened upon it. Thus the fighting caste do in the end serve to protect the species by sacrificing themselves for its good. A family of Termites consists of workers as the majority, of soldiers, and of the King and Queen. These are the constant occupants of a completed Termitarium. The royal couple are the father and mother of the colony, and are always kept together, closely guarded by a detachment of workers in a large chamber in the very heart of the hive, surrounded by much stronger walls than the other cells. They are wingless, and both immensely larger than the workers and soldiers. The Queen, when in her chamber, is always found in a gravid condition, her abdomen enormously distended with eggs, which, as fast as they come forth, are conveyed bya relay of workers in their mouths from the royal chamber to the minor cells dispersed throughout the hive. The other members of a Termes family are the winged individuals: these make their appearance only at a certain time of the year, generally in the beginning of the rainy season. It has puzzled naturalists to make out the relationship between the winged Termites and the wingless King and Queen. It has also generally been thought that the soldiers and workers are the larve of the others: an excusable mistake, seeing that they much resemble larve. I satisfied myself, after studying the habits of these insects daily for several months, that the winged Termites were males and females in about equal numbers, and that some of them, after shedding their wings and pairing, became Kings and Queens of.new colonies; also, that the soldiers and workers were individuals which had arrived at their full growth without passing through the same stages as their fertile brothers and sisters. A Termitarium, although of different shape, size, texture of materials, and built in different situations, according to the species, is always composed of a vast number of chambers and irregular intercommunicating galleries, built up with particles of earth or vegetable matter, cemented

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together by the saliva of the insects. There is no visible mode of ingress or egress, the entrances being connected with covered roads, which are the sole means of communication with the outer world. The structures are prominent objects in all tropical countries. The very large hillocks at Santarem are the work of many distinct species, each of which uses materials differently compacted, and keeps to its own portion of the tumulus. One kind, Termes arenarius, on which these remarks are chiefly founded, makes little conical hillocks of friable structure, a foot or two in height, and is generally the sole occupier. Another kind (Termes exiguus) builds small dome-shaped papery edifices. |Many species live on trees, their earthy nests, of all sizes, looking like ugly excrescences on the trunks and branches. Some are wholly subterranean, and others live under the bark, or in the interior of trees: it is these two latter kinds which get into houses and destroy furniture, books, and clothing. All hives do not contain a queen and her partner. Some are new constructions, and, when taken to pieces, show only a large number of workers occupied in bringing eggs from an old over-stocked Termitarium, with a small detachment of soldiers evidently told off for their protection.

A few weeks before the exodus of the winged males and females a completed Termitarium contains Termites of all castes and in all stages of development. On close examination I found the young of each of the four orders of individuals crowded together, and apparently feeding in the same cells. ‘The full-grown workers showed the greatest attention to the young larve, carrying them in their mouths along the galleries from one cell to another, but they took no notice of the full-grown ones. It was not possible to distinguish the larve of the four classes when extremely young, but at an advanced stage it was easy to see which were to become males and females, and which workers and soldiers. The workers have the same form throughout, the soldiers showed in their later stages of growth the large head and cephalic processes, but much less developed than in the adult state. The males and females were distinguishable by the possession of rudimentary wings and eyes, which increased in size after three successive changes of skin. Thus I think I made out that the soldier and worker castes are, like the males and females, distinct from the egg; they are not made so by a difference of food or treatment during their earlier stages, and they never become winged insects. The workers and soldiers feed on decayed wood and other vegetable substances; I could not clearly ascertain what the young fed upon, but they are seen of all sizes, larvee and pupze, huddled together in the same cells, with their heads converging towards the bottom, and I thought I sometimes detected the workers discharging a liquid from their mouths into the cells. The growth of the young family is very rapid, and seems to be completed within the year: the greatest event of Termite life then takes place—namely, the coming of age of the winged males and females, and their exit from the hive. It is curious to watch a Termitarium when this exodus is taking place. The workers are set in the greatest activity, as if they were

aware that the very existence of their species depended on the successful emigration and marriages of their brcthers and sisters. They clear the way for their bulky but fragile bodies, and bite holes through the outer walls for their escape. The exodus is not completed in one day, but continues until all the males and females have emerged from their pupa integuments, and flown away. It taxes place on moist, close evenings, or on cloudy mornings: they are much attracted by the lights in houses, and fly by myriads into chambers, filling the air with a loud rustling noise, and often falling in such numbers that they extinguish the lamps. Almost as soon as they touch ground they wriggle off their wings, to aid which operation there is a special provision in the structure of the organs, a seam running across near their roots and dividing the horny nervures. To prove that this singular mutilation was voluntary on the part of the insects, I repeatedly tried to detach the wings by force, but could never succeed whilst they were fresh, for they always tore out by the roots. Few escape the innumerable enemies which are on the alert at these times to devour them: ants, spiders, lizards, toads, bats, and goatsuckers. The wasteof life is astonishing. The few that do survive pair and become the kings and queens of new colonies. I ascertained this by finding single pairs a few days after the exodus, which I always examined and proved te be males and females, established under a leaf, a clod of earth, or wandering about under the edges of new tumuli. The females are then not gravid. I once found a newly-married pair in a fresh cell tended by a few workers.

The office of Termites in these hot countries is to hasten the decomposition of the woody and decaying parts of vegetation. In this they perform what in temperate latitudes is the task of other orders of insects. Many points in their natural history still remain obscure. We have seen that there are males and females, which grow, reach the adult winged state, and propagate their kind like all other insects. Unlike others, however, which are always, each in its sphere, provided with the means of maintaining their own in the battle of life, these are helpless creatures, which, without external aid, would soon perish, entailing the extinction of their kind. The family to which they belong is therefore provided with other members, not males or females, but individuals deprived of the sexual instincts, and so endowed in body and mind that they are adapted and impelled to devote their lives for the good of their species. But I have not explained how these neuter individuals, soldiers and workers, come to be distinct castes. This is still a knotty point, which I could do nothing to solve. Neuter bees and ants are known to be undeveloped females. I thought it a reasonable hypothesis, on account of the total absence of intermediate individuals connecting the two forms, that worker and soldier might be in a similar way female and male whose development had been in some way arrested. A French anatomist, however, M. Lespés,* believes to

• “Recherches sur l’Organisation et les Mceurs du Termite Lucifuge, Annales des Sciences Naturelles,” 4™® série, tome 5, fasc. 4 et 5. Paris, 1856. M. Lespés states also to have found two distinct forms of pupa in the same species, one only of which he believes to become kings and queens. I observed nothing of the kind in Termes arenarius. Dr. Hagen mentions, in his monograph, cases of beaked workers and

have found by dissection imperfect males and females in each of the castes. The correctness of his observations is doubted by competent judges;* if his conclusion be true, the biology of Termites is indeed a mystery.

winged soldiers. I always found the beaked individuals to be of the fighting caste; with regard to winged soldiers and other curious forms of pupz which have occurred, they are probably either monstrosities, or belong to species having a peculiar mode of development. I did not meet with such; I found, however, a species whose soldier class did not differ at all, except in the fighting instinct, from the workers. * ¢ Gerstaecker, Bericht iiber den Leistungen, etc., der Entomologie,” 1856, p. 6. Hagen, Linnea Entomologica, 1858, p. 24.

CHAPTER IX.

VOYAGE UP THE TAPAJOS.

Preparations for voyage—First day’s sail—Mocdes of arranging money-matters, and remittance of collections in the interior—Loss of boat—Altar do Chao—Excursion in forest—Valuable timber—Modes of obtaining fish—Difficulties with crew-—

Arrival at Aveyros—Excursions in the neighbourhood—White Cebus and habits and dispositions of Cebi monkeys—Tame parrot—Missionary settlement—Enter the River Cupari—Adventure with Anaconda—Smoke-dried monkey—Boa constrictor—Village of Mundurucit Indians, and incursion of a wild tribe—Falls of the Cupari—Hyacinthine macaw—-Re-emerge into the broad Tapajos—Descent of river to Santarem.