ants' nests. 481 



I will attempt to make a classification of the nests of ants, corre- 

 sponding- approximately to that which I formerly made with a view 

 simply to giving an outline of the variety of the dwellings of ants. 

 Of course, taking into consideration the above-mentioned features of 

 ant architecture, it is impossible to be systematic. 



I.— TAKING ADVANTAGE OF EXISTING CAVITIES. 



Many ants use as nests simply the clefts and crevices of rocks and 

 the space between two stones. They wall up and barricade the exte- 

 rior of the clefts with sand, pebbles, and dry vegetable particles; tliey 

 divide the surface, more or less, into chambers, and leave only one or a 

 few doors (holes) open, to allow themselves egress. Many sjjecies of 

 the genus Leptothorax live in this way, in small colonies, and Plcu/iolepis 

 pygmwa Latr., Cremastogdster aordklida Nyl., Prenolepis lou(jieoniis 

 Latr., etc., in larger colonies, in the same manner. 



Some such species have adapted themselves specially to mankind and 

 occupy the walls of our houses. They know how to avail themselves 

 there of the space between the stones; they bite away the mortar with 

 all their might and carry it away in order to procure for themselves 

 safe and warm lodgings in the neighborhood of our domestic stores, 

 which they pillage thoroughly at the first opportunity. Such ants 

 which have adapted themselves to the walls of our dwellings are Lasius 

 emarginatus Latr., Monomorium pharaonis L. (imported into seaports 

 from the Tropics), Pheidole megacephala Fabr. These insects, as is 

 well known, become house nuisances. 



But other natural cavities are also made use of, esj)ecially those made 

 by other insects. The species of Leptothorax and GolohopHis with us, 

 those of Poly r hack is and Crema-stogaster in tropical countries, know how 

 to make use of the cavities of galls which have been abandoned by the 

 gallfly for their nests. 



Fig. 1, Plate LV, rej^resents a stem gall from Delagoa Bay, South- 

 east Africa, one-sixth smaller than the natural size, which was inhabited 

 by a colony of Polyrhachis r/erstiickeri Forel, and which was sent to me 

 by our countryman, the missionary physician. Dr. Liengme, living there* 

 The Polyrhachis had affixed some of their weaving to the inside, B. 

 The egress opening made by the gallfly was the door of their nest. 

 Cavities made by bark beetles in wood are used among us as nests by 

 the species of Liometopum and Lasius, and especially by Lasius hrunneus 

 Lath., Formica fusca, etc. In the same way the space between the 

 outer layers of the bark of trees (especially the conifers), the under 

 side of the bark of dead trees, the under side of beds of moss, etc., are 

 used as nests by the species of Leptothorax and other small ants. Ants 

 also live frequently in hollow fruits, potatoes, and, above all, in large 

 tropical fruits. Mr. Ortgies found the little Bracliymyrmcx Jieeri For. 

 in the lower part of the pots of the tropical orchids in the Zurich hot- 

 house, which were filled with moss, etc. My friend and colleague, Pro- 

 SM 94 31 



