Ant colonies > Ant hill, housing the commune

Ant hill, housing the commune


Ant hill, housing the communeAnt hill - housing the commune, nesting architecture
The housing of the commune is a duty that springs up side by side with the existence of the commune.

In the typical beginning of an ant community by the single fertilized queen, the first act of the incipient foundress is to scoop out and heap around her, in earth or wood, a cell whose diameter is somewhat greater than the length of her own body.

This is the rudimentary house of the commune - the primitive cave which bounds the architectural aim of most animals, and which is the starting-point with man himself.

With great numbers of species, this cave will be found under a stone. A flat stone, not too large and not deeply imbedded in the ground, if lifted up in the early spring, or at any time during summer, will be found to serve as a rocky roof which overspreads the vestibule and protects certain galleries, halls, and passages into an underground formicary. The mere fact of choosing such a location for a nest is significant; for, besides the protection and defence afforded, the stone absorbs the sun's rays and serves thus as a natural furnace, contributing to the warmth of the ants and of their immature young.

They are simply the primitive cave in multiple, with intercommunicating passages. And they increase on the principle of any other social settlement-to meet the communal growth. Many of them reach immense proportions; most of them are comparatively small.

With the great army of woodworkers the same simple type of architecture prevails, modified simply and not largely by the material from which the public buildings are wrought. The storied subdivisions especially are crowded within a narrower space and are less distinctly marked. One who carefully studies the architecture of a long-established nest of carpenter ants will find himself unconsciously tracing out in miniature pillars, arches, aisles, vaults, and domes of different orders of architecture. It takes but a slight stretch of fancy to imagine that one is gazing upon the ruins of an ancient seat of a diminutive type of his own race, who had carved out their toy-like homes and temples in the solid wood.

One of the most interesting examples of the storied type of underground architecture is that of the honeyants of the Garden of the Gods (Myrmecocystus hortideorum), Colorado; the farthest north they had been observed. The approach to their nest was a small, low, pebble-covered mound with a large central gate which penetrated it vertically for a few inches, and then was diverted into various passages that followed the slope of the ridge on which the colony was planted. In one nest, chosen for complete exploration, excavation was carried forward during three days and several parts of days, two men working with mallet and chisel and with knife in the soft, red sandstone, or "puddingstone," of which the ridge is composed. The entire length of the formicary was seven feet eight inches.

The point at which it ended was forty and a half inches below the level of the main gate and twenty-nine and a half inches beneath the level of the hillside. In all, the ants had excavated thirty-six cubic feet of rock, and this space was honeycombed with galleries and rooms. The latter varied from five to six inches long, three to four wide, and about three-fourths of an inch high. The walls and floors of these rooms were smooth, but the roofs were left in their natural roughness, thus forming a better foothold for the rotunds, or honeybearers, who were perched upon them, clinging thereto with their claws, and closely clustered together.

The occident ant (Pogonomyrmex occidentalis) is closely related to the agricultural ant in structure and habit. But the typical forms vary decidedly in their exterior architecture, the occident having its commune overbuilt with a prominent cone coated with pebbles, while the typical agricultural keeps the space around its gate free from all growth. Both species, like the moundmaking ants of the Alleghanies, are among those that found and maintain vast communities, and therefore have a special interest to us in our present studies. Their homes are often wrought in a tough clay that is almost as hard to excavate as the red sandstone of the Garden of the Gods, and equally taxes the resources of the workers. The arrangement of rooms into stories is here also carried out, and to a surprising extent. In one nest of the occident ant a story was found at a depth of over eight feet beneath the surface.

Those who are curious in such comparisons might find grounds here for a striking parallel between the achievement of an ant three-eighths of an inch high (long), and of a man one hundred and seventy-six times as high (five and one-half feet). Were we to reckon a proportionate rate of progress between the two on the basis of height, our man would have to be credited with a storied structure one thousand four hundred and eight feet deep. Apart from such fanciful comparisons, it is certainly well calculated to excite our wonder that such insignificant creatures can, by their united exertions, bring, about results relatively so vast, unaided by mechanical contrivances.

The numerous chambers which in honey-ant structures are occupied by those living honey-pots, the rotunds, in the occident nests are used as store-rooms. Herein one finds various sorts of seeds put away for food. In a few cases rooms were found filled with husks and apparently sealed up, as if empty spaces had been utilized in the rush of business for "dumping-grounds," to save transporting the waste matter of the seeds to the outer gates and the kitchen middens. Perhaps these "relief chambers" were merely a temporary makeshift, and would have been cleared out in due course had not the commune suffered a destruction as dire as that of ancient Troy or Carthage.

Such great structures as have been described here imply the work of years, and it is probable that some of them were several years old. They showed every mark of such age; in fact, the continuous life of an ant community, in such sharp contrast with that of our hornets and yellow-jackets, which do not survive October, would naturally demand permanent or continuous residences, the permanency of the community and the permanency of their dwelling going naturally hand in hand. By calculations made from the levelled floors of the mountain charcoal-burners, which had been occupied by large mounds since their abandonment, I concluded that some communities of Formica exsectoides were at least thirty years old, and I believe that they remain active for a longer period if unmolested.

Livingstone speaks of ant-hills which dotted the face of the country like haycocks in a harvestfield. In the woods they were seen twenty feet high and forty to fifty feet in diameter. He also notes the fact that these spots are more fertile than the rest of the land, and are the chief garden ground for maize, pumpkins, and tobacco. This statement has a significant bearing upon the part assigned in nature to ants and other insects in making the earth habitable by agricultural man.

The pebble roofing of the cone of the occident ant is a permanent feature - at least, of the immense number seen by me, all were covered with pebbles of the gravelly soil in which they stood. In the vicinage of the Garden of the Gods the pebbles were red sandstone. The mounds in Wyoming observed by Prof. Joseph Leidy were covered with a white stone. Mr. R. Hill saw them on the Sapa Creek, in northwestern Kansas, roofed with pellets of the limestone rock in which the great fossils are found, and in one or two cases even of portions of the fossils. Thus the conditions of the famous riddle of the Judaean Hercules are repeated in this far Occident, and the hymenopterous allies of the bees who nested in the skeleton of Samson's lion burrow and build a home among the bones of extinct creatures of the geologic ages.

The pebbles are handled with ease by the workerants, who nip them with their outstretched mandibles and then move off, rarely stopping en route to adjust the burden or to rest. The body is lifted up, the head well elevated to prevent bumping against the surface, and the load held well to the front or somewhat beneath the body. The portage was amply observed during ordinary excavations, in opening and closing gates, and in repairing breaks caused by rains or purposely made for experiment. In the last-named work the ants would descend to the clearing at the base of the cone, and carry the stones up the slope with as little apparent effort as when moving downward. This, however, must be an easier task than transporting them from distant sites or from their interior beds up the galleries to the surface. The space traversed in this underground portage is sometimes equal to a perpendicular distance of nine feet, which has little mechanical relief from the inclination or roughness of the gangways.

Some of the pebbles have from six to ten times the weight of their carriers. I never saw any copartnerships in these portages. No ant came to aid a struggling worker, and none seemed to need assistance. I have often admired the vigor and skill shown by baggage-porters in shouldering and bearing up several flights of stairs the immense trunks which American ladies take with them on their travels. But here, if we may be indulged in the comparison, is an insect three-eighths of an inch long (and the worker-minors are shorter), who can carry up sharp inclines and perpendicular surfaces, over a distance threehundred times its length, a burden six to ten times its weight. If, as heretofore, we estimate the average man at five and a half feet in length and one hundred and fifty pounds in weight, our baggage-porter would needs carry a halfton trunk up one-tenth of a mile of stairway, to meet on equal footing the emmet athletes of the occident anthills!

The simplest type of ant architecture, as we have seen, is a single cave excavated in the earth, or in wood, or formed by detritus cemented by salivary secretions. This grows into (second) an enlarged chamber or chambers, with vestibule and connecting galleries. Thence (third) developing downward, the simple cave or connected chambers have grown into vast and deep-storied rooms and avenues, like those of the agricultural, occident, honey, and cutting ants.

Expanding in the opposite direction - a development upward instead of downward - (fourth) the little heaps of earth-pellets thrown out around the gate of the cavern home of Pheidole, or the garden Lasius, become (fifth) the great conical structures of the moundmaking ants of the Alleghanies, which are in themselves true habitations. This is an important difference. The cones are thoroughly honeycombed with avenues and rooms, streets and galleries, which are the actual livingquarters of the commune, and form, each mound in itself, into a densely populated city, although in full alliance of citizenship with all like mounds in the vicinage.

We come now (sixth) to a type of structure which characterizes a number of genera in Europe and America, but which is particularly developed in various species and varieties of Cremastogaster. The species of this genus are small, and are widely distributed throughout our territory. They have a heart-shaped abdomen or gaster, flat above and rounded below, and this they have the odd habit of turning up and directing forward, so that it is almost parallel with the line of the thorax.

These ants, besides nesting in the earth near the surface and under stones, are apt to choose a site in a heap of stones on an old stump, or in the debris of fallen and decaying logs. A colony settled among the crannies of a bowlder wall at our country home, Brookcamp, had built a covered approach to their main entrance, using therefor particles of dust, earth, etc., that had accumulated upon the rocks. The nest itself was within the interstices formed by the rounded exteriors of the big bowlders, and was quite out of sight. This covered vestibule was a mild suggestion of the vast mud-covered ways made by the Eciton, or "driver ants," to cover their route when out upon one of their devastating forays.