1907.] Wheeler, The Polymorphism of Ants. 37 



My observations in Colebrook were more extensive and were all made on 

 nests occurring on the slopes of three adjacent hills, which, for present 

 ])urposes, may be designated as the eastern, middle and western hill, cover- 

 ing a strip of territory about a mile and a half long and a quarter of a mile 

 wide, or less than half a square mile. Late in August, 1900, I found a few 

 Xenodusce in two large novoehoracensis colonies on the middle hill. These 

 colonies were essentially like the one seen at Rockford, except that neither 

 contained winged females. My remaining observations relate to a very 

 different ant, Formica sehaufussi var. inccrta Emery, which forms many 

 colonies on the Colebrook hills. This ant, as I have shown in former arti- 

 cles,^ is the normal temporary host of F. dIfficiJis var. consocians Wheeler. 

 The following observations show that it is also the host of X. cava. I may 

 mention incidentally that, although F. rubicunda and its var. subintegra 

 are very common in the same territory, I have never been able to find the 

 beetle in any of their nests. 



F. incerta first impressed me as being a probable host of Xenodusa in 

 1904, when I began to notice pseudogynes in a number of the colonies. 

 August 13 to 24 of that year I took pseudogynes from seven colonies on the 

 eastern and middle hills. Five of these colonies each contained only a 

 few of the abnormal insects, but two, which seemed to be incipient colonies, 

 contained unusually small, pale workers together with numerous pseudo- 

 gynes of the same dimensions. One of the latter colonies, taken August 25 

 also contained a diminutive but perfectly developed female (microgyne). 

 This colony was kept in an artificial nest till September 16. The numerous 

 pseudogynes behaved in all respects like normal workers. They fed one 

 another, carried the cocoons away when the nest was illumined, etc. In 

 another colony that was used for some experiments with F. consocians, 

 two pseudogynes, which had hatched late in August, 1904, lived till /Vpril 

 9 of the following year, and this notwithstanding the fact that one of them 

 had much crippled antenna? and had to be fed and cared for by the normal 

 workers during the whole period. 



A remarkable colony was found during the early morning of August 13. 

 The preceding night had been unusually cold so that the ants were still very 

 inactive and I was able to capture the entire personnel. It consisted of the 

 following: a single dealated female, to all appearances the mother of the 

 colony; 8 perfectly normal winged females; 46 normal workers; 2 larvae; 

 193 pseudogynes, and 12 ])seudogyne pupjie. In this colony, therefore, 

 nearly 80% of the personnel were pseudogynes! In size these averaged like 



1 A New Type of Social Parasitism among Ants. Bull. Am. Mus. Nat. Hist. XX, 1904, 

 pp. .347-37.5; and On the Founding of Colonies by (Jiieen Ants, witli Six-cial Kffcicnee to tlie 

 Parasitic and Slave-making Species. Ibid., XXII, 1906, pp. 33-105. 



