FOKMICARLE. 183 



for a nest. The F. sanguinea is not so helpless, "they assist 

 their negroes in the construction of their nests, they collect their 

 sweet fluid from the Aphides ; and 

 one of then* most usual occupations 

 is to lie in wait for a small species 

 of ant on which they feed ; and when 

 their nest is menaced by an enemy 

 they show their value for these faith- 

 ful servants, by carrying them down 

 into the lowest apartments, as to a 

 place of the greatest security." 

 (Kirby.) Pupae of both of the slave- 

 making species were placed in the 

 same formicary by Huber, where they Fig. no. 



were reared by the "negroes," and on arriving at maturity 

 "lived together under the same roof in the most perfect amity," 

 as we quote from Kirby. Darwin states that in England, F. 

 sanguinea does not enslave other species. 



In this country Mr. J. A. Allen has 

 described in the Proceedings of the 

 Essex Institute, vol. 5, 1866, a foray 

 of a colony of F. sanguinea upon a 

 colony of a black species of Formica, 

 for the purpose of making slaves of 

 them. 



Formica Pensylvanica, our largest 

 species, is found in oaks and decay- 

 Fig. 111. ing trees, while F. herculanea Latr. 

 burrows in the earth, its hole opening beneath stones and sticks. 

 Gould, who wrote in 1747, states that there are two sizes of 

 workers of the common European Formica rufa, and flava; 

 one set of individuals exceeding the other by about one-third. 

 Kirby states that in his specimens "the large workers of For- 

 mica rufa are nearly three times, and of F. flava , twice the 

 size of the small ones." Mr. E. Norton describes F. fulvacea 

 (Fig. 110, worker minor), and also Tapinoma tomentosa (Fig. 

 Ill, worker major ; antennae broken off), from Mexico. 



The tropical genus Polyrliacliis includes, according to Smith, 

 all those species that closely resemble Formica, but which 



