372 ants' nests. 



different way. Thus, Mr. Wroughton once, in an exceptional case 

 in India, found Sima iiigra^ Jerdon, living in an acacia thorn. 



7. — Compound Nests. 



In the Communications of the Siviss Entomological Society, Vol. 

 III., Part 3, 1869 ("Observations on the Habits of Solenopsis 

 fugax " ), I first called attention to the fact that two hostile species 

 of ants can live in nests which are regularly intercalated. In my 

 Foiirmis de la Suisse {\Z']6^, I showed that such relations occur 

 very frequently and more or less accidentally among many species 

 of ants, especially under stones that are well adapted to nests and 

 greatly in demand ; while, in Solenopsis fugax, Latr., *' double 

 nests" form a very ordinary, in fact, the most ordinary, occurrence, 

 at least in our meadows. Wasmann (2%^ Co?npound Nests and 

 Mixed Colonies of Ants, Miinster i., W., 189 1, Aschendorff's) has 

 corroborated and supplemented my observations on this subject. 

 Instead of the name " double nests," used by me, he has intro- 

 duced the more correct expression, " compound nests " (to be 

 translated into French by " nids composes"). In fact, these nests 

 are not unfrequently threefold, and even fourfold — that is to say, 

 the nests of from three to four different and hostile species of ants 

 are built into each other, without, however, having any open com- 

 munication with each other. If the partitions are destroyed, war 

 ensues immediately. The worker of Solenopsis fugax is a puny, 

 yellowish ant, hardly two millimetres in length, but the females grow 

 to an imposing size, and look like giants by the side of the workers. 

 This species is in the habit of digging its nests in the thick walls 

 of the nests of the ants of the larger species, and in such a manner 

 that, wherever there is room, large halls are constructed (Fig. 6, 

 S), in which the females and the males are comfortably lodged 

 with their large pupae and larvae, while small passages connect 

 these halls. Extremely small passages, not visible in the figure, 

 afford the workers exclusively admission to the chambers of the 

 host ant (Fig. 6, For.). According to my observations and those 

 of Wasmann, Sokftopsis fugax lives like a thief and little robber, 

 at the expense of its involuntary host. The little workers make 

 their way through extremely small passages to the pupa and larva 



