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8 How the White Ants Battled Against Drought

Maeterlinck quotes that the great explorer and naturalist Livingstone was so completely baffled by the mystery of the source of the termite water supply that he eventually came to the conclusion that the insects had discovered the secret of manufacturing water synthetically. I found this very interesting, because in August 1922 I wrote an article on the puzzling question of termite water supply in which I stated I had at one time come to the conclusion that the termites manufactured water out of its constituent gases.

I was then unaware of Livingstone's statement. The notes for my article were written in Waterberg towards the end of a three years' drought - a drought which had produced a state of desiccation unparalleled in the experience of the oldest settlers. Not only was there no blade of green grass, but, as deep down as one could dig, the soil seemed utterly destitute of water.

During this time a number of termite nests were opened and in all of them the normal water supply seemed undiminished. Not only does ninety per cent

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of the termites' body weight consist of water, but all the fungus gardens (in the nests of gardening species) were moist, and the atmosphere of the royal cavity was, as usual, saturated with heated water vapour. Whence did this apparently unlimited supply come from?

The termites could not procure it out of the soil, because the earth was so parched that hardly a film of vapour could be produced by distillation of subsoil. The only other possible sources of supply were dew and the sap of living plants. In time, careful observation excluded both these. It was just a lucky chance that put us on the track of the surprising truth. The late Mr Wessel Wessels, a fine practical naturalist and a keen observer, who, as recorded in The Star, was killed by a mamba some years later, first suggested a possible source of supply. He told us he had found termite shafts in the walls of deep wells on two occasions in Bechuanaland. These shafts had been disclosed by the digging of the wells.

The termites went down these shafts to the level of moist earth and from there brought their water to the ant-hill on the surface. This seemed almost as incredible as the theory of the manufacture of water - and yet it was the true explanation. Very shortly after this suggestion was made, we were informed that a well had been sunk high on a hillside on the farm Rietfontein No. 1368, and that a termite shaft had been disclosed going down to a depth of sixty-five feet from the surface.

We had an opportunity of observing for several months this tremendous feat of engineering and the use to which it was put by the termites, and nothing I had previously observed in the life of the white ant was more absorbingly interesting. The well had originally been sunk at a spot pointed out by a waterdiviner, but at a depth of sixty-five feet the work was stopped because no moist earth had yet been found.

In the northern wall of the well was a two-and-a-half inch wide termite shaft which went down to the bottom of the well and disappeared in the ground. The ant-hill to which this shaft belonged was situated a few paces from the edge of the well. We carefully opened up the gallery for its entire length, and disclosed some of the fungus gardens by means of a small aperture which could be closed when not in use.

The nest belonged to a species in which soldiers and workers were not so widely differentiated as in Eutermes (the common high-veld termite largely dealt with in the previous articles). It soon became evident that the termites had been placed in a tragic difficulty by the opening up of their shaft. Although, above everything, they hated the light, they were compelled to use the shaft since a cessation of the water supply, even for a single day, would mean the death of the community.

And so we saw an endless stream of workers going into the depths on the left-

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hand side of the shaft, and another endless stream coming up on th right-hand side. From time to time, and always at night, they made futile efforts to cover in the passage, always commencing work at the lower end. As regularly, we broke up the roofing next day. We observed them at all hours of the night and day. They never ceased work for an instant, and by marking individuals with dots of aniline dye we ascertained that the same individuals worked night and day.

They never slept or rested. On the average it took an individual just over half an hour from the time he left the nest to the time of his return. It struck me at once as very singular that, although the shaft ziz-zagged in a plane east and west, there were no bends north and south. That is how it came about that it was exposed for its entire length in the northern wall of the well.

What was the cause of this? The only possible explanation seemed to me to be that in their labours the termites were affected by the terrestrial magnetism, since they invariably build their long hills with one end pointing to the magnetic north.

It was evident that the most desperate battle of our water-carrying termites was directed to the preservation of the fungus gardens. We could watch a bit of their work. The garden we had partially exposed was apparently the one in most danger. There was a visible circle of desiccation and, concentrated along this line, was an unbroken file of water-carriers from the shaft, irrigating the dying plants. During the hot hours of the day, when evaporation was at its height, the drought invariably gained one or two inches. During the cool hours of the night the damage was as systematically repaired.

At intervals down the shaft were small cakes of the cellulose layer on which they cultivate the edible fungus. In the beginning, the deepest ones had growing fungi on them and the workers made desperate efforts to keep them moist and to roof them in during the night. These cakes were seed beds and from these they procured spores for replanting the dying gardens in the nest itself. It was, of course, a great saving of labour to have these beds as near the water supply as possible. The greatest activity prevailed during the darkest hours of the night. There was quite certainly more speed and also an increase in numbers. Descending and ascending streams were thicker during the night. It seemed as if workers employed on other work during the day were concentrated on the irrigation shaft at night in order to repair the ravages of rapid evaporation. During the night this increase of activity and speed gave the impression of alarm - of the fever of a great battle. And this impression was intensified by the incessant trumpeting of the workers, which was clearly audible in the stillness of the night.