their dwellings, towns, and their vicinity in a state of comparative cleanliness. The dread of them is upon every living thing.

'Their entrance into a house is soon known by the simultaneous and universal movement of rats, mice, lizards, Blapsidæ, Blattidæ, and of the numerous vermin that infest our dwellings. Not being agreed, they cannot dwell together, which modifies in a good measure the severity of the Drivers' habits, and renders their visits sometimes (though very seldom in my view) desirable.

'They move over the house with a good degree of order, unless disturbed, occasionally spreading abroad, ransacking one point after another, till, either having found something desirable, they collect upon it, when they may be destroyed en masse by hot water.

"When they are fairly in, we give up the house, and try to await with patience their pleasure, thankful, indeed, if permitted to remain within the narrow limits of our beds or chairs.'

These ants will soon destroy even the largest animal if it is confined. In one case Savage saw them kill near his house a snake four feet long. Indeed, it is said that they have been known to destroy the great python, when gorged with food and powerless. The natives even believe that the python, after crushing its victim, does not venture to swallow it, until it has made a search, and is satisfied that there are no Drivers in the vicinity! It is very remarkable that these hunting

ants are blind. They emerge, however, principally by night, and like some of the blind hunting ants of Brazil (Eciton vastator and E. erratica), well described by Bates,1 prefer to move under covered galleries, which they construct rapidly as they advance. The column of foragers pushes forward step by step, under the protection of these covered passages, through the thickets, and on reaching a rotting log, or other promising hunting ground, pour into the crevices in search of booty.'

26

The marauding troops of Ecitons may, in some cases, be described as armies. Wherever they move,' says Bates, the whole animal world is set in commotion, and every creature tries to get out of their way. But it is especially the various tribes of wingless insects that have cause for fear, such as heavy-bodied spiders, ants of other species, maggots, caterpillars, larvæ of cockroaches, and so forth, all of which live under fallen leaves or in decaying wood. The Ecitons do not mount very high on trees, and therefore the nestlings of birds are not much incommoded by them. The mode of operation of these armies, which I ascertained, only after long-continued observation, is as follows: The main column, from four to six deep, moves forward in a given direction, clearing the ground of all animal matter dead or alive, and throwing off, here and there, a thinner column to forage for a short time on the

The Naturalist on the River Amazon, vol. ii. p 364. 2 Ibid., p. 358.

F

flanks of the main army, and re-enter it again after their task is accomplished. If some very rich place be encountered anywhere near the line of march-for example, a mass of rotten wood abounding in insect larvæ, a delay takes place, and a very strong force of ants is concentrated upon it.'

1

Belt, also, has given 1 an excellent account of these Ecitons. He observed that spiders were peculiarly intelligent in escaping them, making off several yards in advance; and not like cockroaches and other stupider insects, taking shelter in the first hiding-place, where they were almost sure to be detected. The only chance of safety was either to run right away or to stand still. He once saw a Harvestman (Phalangium) standing in the midst of an army of ants with the greatest circumspection and coolness, lifting its long legs one after the other. Sometimes as many as five out of the eight would be in the air at once, but it always found three or four spots free from ants, on which it could safely place its feet. On another occasion, Belt observed a green leaf-like locust, which remained perfectly still, allowing the ants to run over it. This they did, but seem to have been quite deceived by its appearance and immobility, apparently taking it for a leaf.

In other cases, insects mimic ants, and thus escape attack or are able to stalk their prey. Belt mentions a spider which in its form, colour, and movements so

1 The Naturalist in Nicaragua, p. 17.

much resembled an ant, that he was himself for some time deceived.

Nor are ants without their enemies. We all know how fond birds are of their larvæ and pupæ. They have also numerous parasites. I have already alluded to the mites which are often found in ants' nests. These are of several kinds; one of them, not uncommon in the nests of Lasius flavus, turned out to be a new species, and has been described for me by Mr. Michael (see Appendix).

Certain species of Diptera, belonging to the family Phoridæ, are also parasitic on ants. As already mentioned, I forwarded specimens to Mr. Verrall, who finds that some of them are a new species of the genus Phora, and that among them is also the type of a new genus, which he proposes to call Platyphora, doing me the honour of naming the species after me. I subjoin his description in the appendix.

But the social and friendly relations which exist between ants and other animals are of a more complex and much more interesting character.

It has long been known that ants derive a very important part of their sustenance from the sweet juice excreted by aphides. These insects, in fact, as has been over and over again observed, are the cows of the ants; in the words of Linnæus, 'Aphis formicarum vacca.' A good account of the relations existing between ants and aphides was given

more than a hundred years ago by the Abbé Boisier de Sauvages.1

Nor are the aphides the only insects which serve as cows to the ants. Various species of Coccidæ, Cercopis, Centrotus, Membracis, &c., are utilised in the same manner. H. Edwards 2 and M'Cook 3 have observed ants licking the larva of a butterfly, Lycana pseudargiolus.

The different species of ants utilise different species of aphis. The common brown garden ant (Lasius niger) devotes itself principally to aphides which frequent twigs and leaves; Lasius brunneus, to the aphides which live on the bark of trees; while the little yellow ant (Lasius flavus) keeps flocks and herds of the root-feeding aphides.

In fact, to this difference of habit the difference of colour is perhaps due. The Baltic amber contains among the remains of many other insects a species of ant intermediate between our small brown garden ants and the little yellow meadow ants. This is possibly the stock from which these and other allied species are descended. One is tempted to suggest that the brown species which live so much in the open air, and climb up trees and bushes, have retained and even deepened their dark colour; while others, such as Lasius flavus,

1 Observations sur l'origine du miel, par l'Abbé Boisier de Sauvages, Jour. de Physique, vol. i. p. 187.

2 Canadian Entomologist, January 1878.

The Mound-making Ants of the Alleghanies, p. 289.