Harvesting Ants and Trap-Door Spiders / Notes and Observations on Their Habits and Dwellings

by John Traherne Moggridge

The ants work very frequently at night during the dark,[32] and this is the case in the wild as well as in the captive nests. A friend, at my request twice visited a nest of structor ants in the garden of an hotel at Mentone, when it was quite dark (in March, between seven and eight o'clock P.M.) and no moon, but the light of a candle showed that the workers, both large and small, were busily engaged in carrying into the nest seeds which had been purposely scattered in their neighbourhood. I have myself seen Pheidole megacephala similarly engaged at about nine P.M. on a warm night in April, when it was perfectly dark, not even the stars showing; but in this case the ants were collecting from the weeds in the garden. On the same occasion I also observed long and active trains of Formica emarginata

[32] This bears out the much-questioned assertion of Aristotle, though he only claimed that ants work "by night when the moon is at the full."—Hist. Anim., lib. ix. cap. xxvi.

Before leaving Mentone, on May 1, I turned out this second captive nest, and found that the colony appeared perfectly healthy, and did not seem to have diminished materially in numbers. The queen ant and the larvæ seemed to be in just the same state as when they were taken. The earth in the lower part of the jar was honeycombed with galleries, granaries, and cells, constructed quite as in the wild nests, but more crowded together. The granaries were in many instances full of seeds, which, though very wet, [the surrounding soil being extremely moist on account of there being no drainage to carry off the water which I was obliged to sprinkle from time to time over the surface of the nest], still showed no trace of germination that I could detect. The ants were therefore able to exercise the same influence over these seeds, under the strange conditions of their captive state, that they do in their natural homes.

The foregoing remarks, as has been stated above, refer for the most part to only one of the three kinds of harvesting ants which I have observed on the Riviera—that is to say, to Atta barbara, the jet-black ant.

As far as the manner of collecting and storing the seed is concerned, all that has been said of Atta barbara applies with equal truth to A. structor.

A. structor is, however, less frequently seen above ground from December to March than barbara, and is more frequently found in or near the streets and gardens of a town.

The fourth species, on the other hand, the little Pheidole megacephala, differs in several particulars. This ant appears to shun the daylight, and to be most active at night, when, in the warm weather at the end of April, it may frequently be seen carrying large quantities of seeds into its nest. I have rarely observed it at work in the daylight, so that my knowledge of its habits is but small. Nor have I succeeded in discovering its subterranean granaries, though I have opened several nests. Still, I believe that it is a true harvesting ant, and not merely a casual collector of seeds. Of the habits of Pheidole pallidula, a very closely allied and similar species, but one less frequently met with, I cannot speak with certainty, though it is quite possible that it also may be a true harvester, in which case it would add a fifth species to this class.

Both Pheidole megacephala and Ph. pallidula appear to remain inactive, or nearly so, during the months from November to April, and it is probable that they are only to be seen in full activity during the summer when I am not there to watch them.

There can be little doubt that any naturalist who will take the pains to note the habits of ants on the shores of the Mediterranean through June, July, August, and September, might collect a most interesting series of observations on harvesting and other species, and add to, and perhaps modify, those which my limited opportunities have enabled me to make.

There are three other ants[33]—namely, Formica emarginata, F. fusca, and Myrmica cæspitum, which may also occasionally be found carrying a few seeds, but this is the rare exception, as far as my experience goes, these species living on honey dew, sweet secretions, and animal matter, like the great majority of ants all over the world. I have never found seeds in the nests of any ants except those of Atta barbara and A. structor, though I have carefully searched for them in most of the nests of the sixteen species of ants whose habits I have watched.