Ant colonies > Ant nests > Suspended ant nests

Suspended ant nests

The suspended ant nests, like the majority of epiphytic plants, are found only in the forests of the tropics. They are true constructions throughout, consisting of earth, carton or silk, built so as to enclose anastomosing chambers and galleries. Earthen suspended nests, or "ant-gardens," were discovered by Ule in the forests of Brazil. They are constructed by several species of ants (Azteca olithrix, ulei and traili and Camponotus femoratus), which carry up particles of earth and build them into spherical masses, sometimes of the size and appearance of bath-sponges around the branches of trees.

According to Ule, the ants even plant the seeds of epiphytes in this earth, so that it may be held together by the roots and thus acquire greater consistency for the support of the enclosed galleries. This statement is open to some doubt, as it is evident that such suspended earth-masses in a humid tropical forest may easily become seeded with epiphytes without the intervention of the ants. Even in temperate regions there is a slight approach to this kind of nest in the masses of earth which are sometimes built up around the stems of herbaceous plants by certain European ant species of Lasius, Myrmica and by Tapinoma erraticum. I have seen similar nests fashioned by Myrmica canadensis in the bogs of New England.

Although a few ants in temperate regions are able to make carton nests, the majority of carton-builders are found in the tropics and it is only in these regions, as I have said, that the nests are suspended from trees. In Europe Lasius fuliginosus and Liometopum microcephalum construct carton nests in hollow logs, and in the Western and South­western States Liometopum apiculatum and Cremastogaster lineolata make similar nests under stones. In the tropics suspended carton nests are built by ants belonging to the genera Camponotus, Polyrhachis, Azteca, Dolichoderus, Cremastogaster, Macromischa and Tetramorium, representing the three more specialized subfamilies.

The genera Azteca and Cremastogaster, the former a cosmopolitan, the latter an exclusively neotropical group, seem to contain the greatest number of carton­building species. Certain Indian and African species of Cremastogaster have long been known to construct large spherical or egg-shaped paper formicaries.

Many species of the highly arboreal genus Azteca build carton nests, and these show considerable range of variation in form and structure. The suspended nests of A. aurita, mathildae trigona, multinida, lallemandi, schimperi, etc., are more or less egg-shaped or cylindrical and resemble the carton nests of termites and Cremastogaster. Other species (Azteca barbifex, stalactitica, decipens and lanians) build their paper nests in the form of long pendant stalactites. A. hypophylla lives under leaves whose edges are attached to tree-trunks by means of carton, A. xysticola lives in meandering carton galleries on the surface of large stones in forests, and A. muelleri, constructor and nigriventris use more or less carton in the construction of their galleries in plant cavities.