(B) Familiar Ants (Formica) (cont.)
Leafcutting Ants (Oecodoma). Gigantic Black Ants. Pseudomyrma bicolor. Soldier Ants.
The Leaf-cutting Ants (Oecodoma) are noted pests of central and tropical America; and, as is implied by their name, commit fearful havoc among trees, laboriously and persistently carrying off in their mouths, piece by piece, the foliage of trees and shrubs. The orange, lemon, and mango trees in particular have suffered from their attacks. Carbolic acid has been tried with success as a remedy against these ants, the use of this antiseptic killing large numbers; and corrosive sublimate in powder, sprinkled across their paths, has a deadly effect upon the lead-cutters. Coal tar has also been employed against them.
Gigantic black ants, averaging an inch in length, are found in Central America. They are notable as being solitary in their habits, and possess well-developed eyes and formidable stings. These forms contrast with the gregarious and social ants, in which the eyes are comparatively weak, or may be rudimentary.
Certain curious little ants (Pseudomyrma bicolor) inhabit the hollow thorns of the "bull's horn" acacia of Central America. The horn-like thorns form the nest, the aperture being situated near the tip of the thorn. These ants preserve the plant from the attack of the Leaf-cutting Ants, and also from mammals feeding upon it. The ants obtain a supply of food from the plant, in the shape of a honey-like secretion, found in a gland situated at the base of the leaflets. Protected by, and at the same time protecting the plant, the intimate relations between the acacia and the ants may be argued to possess a deeper significance than relates to a merely casual or chance connection.
The Cecropia, or trumpet tree of central America, is tenanted by ants, which obtain a sweet fluid, through the agency of brown scale-insects (Coccidae), kept by them in the cells of the trunk.
This recalls the case of the aphides, or ordinary plant lice, the ants sucking the fluid from the scale-insects through a dorsal or back-pore. The queen-ant in her royal cell is attended by a special bevy of Coccidae, who supply her with the requisite food. The Coccidae in America take the place of the European aphides as ant-cows, but the tropical ants appear to attach themselves to other insects also. Thus, the leaf hoppers (Membracis) are attended by ants, for the sake of the honey which the larvae exude. Those insects which are attended by ants are protected from the attacks of other animal forms; and the shelter given to the ants thus serves to protect the tree or shrub, and to save it from becoming exterminated.
The "soldier ants," referred to in the foregoing account of the Foraging Ants, are not peculiar to that race, many other species also possessing "soldiers." These forms, has been already stated, appear to be merely neuters which have the jaws very largely developed, for the protection of the true neuters or workers, and for the defence of the nest generally. This further subdivision of the ant-community would seem to indicate an additional approach to the social arrangements which characterize the human state.
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