THE NATURALIST.

Otago Witness, Issue 3097, 23 July 1913, Page 68

THE NATURALIST.

By James Drummond, F.L.S., F.Z.S.

IN TOUCH WITH NATURE. NOTES ON NATURAL HISTORY IN NEW ZEALAND.

A correspondent at Maeterton, who has made a close study of bird-life in New Zealand, has sent me a small glass tube containing a few members ol an ant colony. “.A short time ago,” he says, “1 was in country which, some 30 years ago, was covered with part of a vast forest called the Seventy-mile Bush, that extended up to Hawke’s Bay. It is now covered with grass and rotting timber, and is no place for an ornithologist, but I discovered something that interested me and, I have no doubt, will interest you. When turning over a piece of rotting matai I was surprised to see a large colony of ants, specimens of which 1 send you. These insects were sluggish and seemed to be torpid, and only a few of them were seen; but the members of another colony, discovered later, were quite as active as ants usually are.” In both colonies there were other specimens, which on examination proved to be larvce of other insects. It is regrettable that the correspondent, an able and careful observer in other branches of the dominion’s natural history, did not give the ants more attention. About 16 species of native ants, belonging to three subfamilies and ten genera, have been described, some o! the descriptions being by the greatest authorities in the world on this very interesting group of creatures, but their habits have not been extensively observed, and little is known of them and their ways. Most of the knowledge available has been supplied by Mr W. W. Smith, of New Plymouth, a keen, enthusiastic, and versatile worker. Apparently New Zealand ants possess the same general characteristics that Lubbock, Swammerdam, Huber, Bates, and other writers have described as belonging to the species of other countries. It is certain that the New Zealand ants are quite as quaint and instructive as other ants and afford the same object-lesson in industry. I can find no records of ant-hills in New Zealand, and this leads to the conclusion that the native ants do not build little hillocks, but make alj their nests under logs or stones. In different parts of the Canterbury Plains ant colonies are very numerous. There is ongenus, Monomorium, which seems to be well represented on the plains. It has been found under stones in open situations in Westland, on the outskirts of the forests and in the warm valleys of the plains, in old river beds, and in the forests of the North Island. Mr Smith suggests that, in order to study the insects’ habits, the stone or log that covers the nest should be gently raised. In that way the natural conditions of the nest are disclosed. In many cases nests are made close to plants which attract aphis and cocdds, insects upon which the ants feed. The rooks of Acama miorophylla, a plant allied to the pin-piri, are specially liable to attacks by coccids and a white woolly aphis, and some antp make clear passages alongside the routs .infested with the parasites. These passages are frequently traversed by the ants, which have been .seen moving leisurely over the aphids and cocdds, gently stroking them with their unioniiob, and moving their woolly and cottony secretions. It is believed that i he secretions contain a sweet moisture, which attracts the ants, and is greatly relished by them. Sometimes many of the ants may he seen moving about a nest with minute particles of the fine cottony substances adhering to their heads and mandibles. There is a glossy black species of ant, found under Boulders in the bed of the Ashburton River, which seems to protect

colonies of coccids that are parasitic on the roots of several plants. Mr Smith Ims seen adult female coccids, covered with masses of the cottony secretions, walking leisurely about the courts of a nest, and a little black ant struggling ineffectually to carry off some of these large coccids. After several failures the ant returned, walked backwards, and dragged the coccids into the galleries. The walks and courts of this black species of ant, when seen through a lens, show perfection of workmanship. In some of the nests there have been found groups of minute yellow' eggs, with eggs of the- normal white or reddish-white colour. On- one occasion Mr Smith found several nests, close together, containing clusters -of queen eggs, or those which develop into queens, while there were only a few eggs of workers. In the bed of the Ashburton River there is a very small species of native ant, with a clear brown colour, which usually makes its nest in sandy places, amongst stunted vegetation. " Minute star-like coccids associate with these ants, and feed upon the plants. The colonies formed by this species are small, but they increase during the summer, and then dozens of the adult female coccids may be seen leisurely walking about in the nestsOn one occasion Mr Smith found a colony under a stone that was lying near some plants of the dwarf Garmichselia. Ihe roots of the plants were growing horizontally under the stone, and as the fine sand had been removed from the roots, they were clear in the nest. Many coccids had attached themselves to the rotes, and worker ants seized some of these coccids and removed them to dark recesses in the nest. To do that they had to climb about 2in of the perpendicular wall of the nest. Each ant seized a coccid, returned along the root, walked down the wall, and disappeared in the recesses of the nest. One species, Monomorium nitidum, evidently does not keep coccids. Large communities of this species, numbering about 800 individuals, have been found without any coccids or other foreign insects. In a nest of this species Mr Smith found 10 queens secreted in different parts of the nest—some in cool, moist chambers ITin down in the shingle. Nitidum, by the way, has received credit for being the most active of all the native ante, and it vigorously assails all intruders near its nest. The largest New Zealand species is Huberia striata. It lives in fairly large colonies in old river-beds on the Canterbury . Plains, but the largest specimens of the species arc found in the limestone districts, or in the warm rocky valleys near the main range of the Southern Alps. At Albury there are great colonies beneath detached'' pieces of limestone lying amongst tussocks at the base of a sloping bed of debris beneath large rocks. In the courts, and along the tracks used by the ants, there have been found pretty little shells belonging to a mollusc named Laorni haasti, which is very common amongst the broken rocks. Ail the shells found were empty, and some were bleached; but It is not known whether they crept into the nests or were carried there by the industrious ants. They have been seldom found under stones where there were no ants, and when they were found there they were usually alive. Hr Smith thinks, therefore, that they were carried into the nests, and were used by the ants for food. He states that anybody who gently turns over a large stone and looks into a populous colony of Huberia striata will see an enchanting scene in ant life. From September to January the courts and galleries in the nests contain groups of eggs and larvae of different ages. When light and air me admitted to the -nest the eggs and larvae are rapidly seized by the workers and borne away to places of safety in the inner galleries. The queens are very timid, and disappear into their chambers as soon as the stone is raised. When the structure of the galleries lias been examined, some difficulty has been experienced in tracing the queens to their hidingplaces. The galleries usually ramify in many directions, and often to a very considerable depth, especially when the nest is made on stony ground. Young winged queens, males, and neuters of Huberia striata appear in their nests early. They begin to appear about November 10, and their numbers increase until they swarm in February. For weeks before the young ants take flight the nests are crowded with the winged insects waiting for the proper time and conditions. A calm, sultry day is chosen, and the young ants then sot out in great numbers to establish new colonies. Some years ago Mr Smith recorded his encounter with a swarm of ants between Ashburton and Mount Somers. He was driving across the plains with a friend, and they stopped to see the swarm passing. In a few seconds the horse, the trap, and the occupants wore covered with ants. A wire fence that ran along the road held millions of them. Many of those on the. fence had cast their wings, but others took flight again and mingled with the swarm. It seemed to be densest between 6ft and 10ft from the ground. The speed was about a mile an hour. As it swept onward, individuals dropped out, alighted on tussocks, shook off their wings, and disappeared in the grass. I will give one more note from Mr Smith’s observations to show that New Zealand ants are not wanting in intelligence. A friend of his informed him that ants were busy removing eggs from their nest under stones in a river-bed. When the place was visited a few days later the ants were found to be on much higher ground than they occupied when the migration began. The object of the movement was quite clear. The river had been slowly rising, and the water had penetrated the coarse shingle to within a few inches of the old nest. The ants, realising the danger days before it arrived, took measures to protect theix treasured possessions.