Page:Popular Science Monthly Volume 54.djvu/85

From Wikisource
Jump to: navigation, search
This page has been proofread, but needs to be validated.
77
THE HERDS OF THE YELLOW ANT.

little creatures and appear to be paying them some kind of court. When I cut the vine for photographic purposes, six or eight ants were standing about the large individual mentioned above; they soon became aware that some dire calamity had happened, or was about to happen, either to their beloved herd or to themselves, and, becoming frightened, soon abandoned cattle and pasture and fled away in panic terror. I had hoped to photograph them in situ, but found this to be impossible with the instruments at my disposal.

The ants do not "milk" these white aphides, neither do they eat the excrementitious substance on their backs. The white individuals, however, seem to be factors in the social economy of the herd, for the ants move them, on occasions, along with the herd to other pastures. Once I saw an ant pick up a white aphis and carry it to a leaf some little distance away from the colony; she then returned, picked up a gravid nectar-producing aphis, and carried her to the spot where she had left the white individual. In a few days a fine herd of "milkers" was to be seen grazing in the new field. I judge from this that these white aphides are in some way useful to, if not absolutely necessary for, the welfare of the herd.

PSM V54 D085 An aphis lion.png
An Aphis-Lion.

The winged females have both compound eyes and ocelli, or primitive eyes, yet they seek the under surface of the leaf, thus seeming to prefer the more subdued light to be found there. The young are always deposited on the under surface of the leaves; in a few days, however, they either migrate of their own accord to the more succulent stems or are carried thither by the ants, which never cease to watch over and care for them.

In order to test this guardianship, I have frequently wounded the vine below a colony of aphides, thus cutting off, to a certain extent, the flow of sap. The ants would soon discover this and would at once begin to move the-herd to another vine. The aphis is provided with boring and suction organs somewhat similar to those of the mosquito. In point of fact, it is interesting to note that the ancestors of the mosquito, in all probability, lived wholly on the juices of plants; hence, in this respect, the resemblance is more real than apparent. Aphides, also, like mosquitoes, have the curious habit of elevating their bodies, "standing on their heads," after they