350 ants' nests. 



leave only one or a few doors (holes) open, to allow themselves 

 egress. Many species of the genus Leptothorax live in this way, 

 in small colonies, and Plagiokpis pygmcea, Latr., Creinastogaster 

 sordidula, Nyl., Prenolepis longicornis, Latr., etc., in larger colonies, 

 in the same manner. 



Some such species have adapted themselves specially to man- 

 kind 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 neighbour- 

 hood 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., Motio- 

 morium 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, especially 

 those made by other insects. The species of Leptothorax and 

 Colobopsis with us, those of Polyrhachis and Cremastogaster in 

 tropical countries, know how to make use of the cavities of galls 

 which have been abandoned by the gall-fly for their nests. 



Fig. I, PL XIX., represents a stem-gall from Delagoa Bay, 

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

 was inhabited by a colony of Polyi-hachis gerstdckeri, Forel, and 

 which was sent to me by our countryman, the missionary physi- 

 cian, Dr. Liengme, living there. The Polyrhachis had affixed 

 some of their weaving to the inside, B. The egress opening made 

 by the gall-fly was the door of their nest. Cavities made by bark 

 beedes in wood are used among us as nests by the species of 

 Liometopuin and Lasms, and especially by Lasius brunneus, Latr., 

 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 trojjical fruits. Mr. Ortgies found the little 

 Brachymyrmex heeri, For., in the lower part of the pots of the 

 tropical orchids in the Zurich hot-house, which were filled with 



