74 Bulletin American Museum of Natural History. [Vol. XXII, 



6. Formica sanguinea rubicunda Emery. 

 Two forms of the sanguinary ant are pretty generally distributed 

 over the northern portion of the United States: Formica sanguinea ru- 

 bicunda Emery and its variety suhintegra Emery, the former with a 

 black, the latter with a brown or even yellowish, gaster. In most 

 localities, so far as I have been able to observe, the var. suhintegra is 

 the more common and often the only form represented. This is cer- 

 tainly true of the region about New York where I have hitherto 

 found only suhintegra. At Colebrook, Conn., where both occur in the 

 same localities, there is also another much rarer form, which agrees 

 very closely with Forel's description of the subspecies aserva and with 

 types of this form which he kindly sent me some years ago. I have 

 used females of all three of these forms in my experiments, but the 

 results obtained with suhintegra and aserva leave much to be desired. 

 During the last days of June I found a large army of ruhicunda in 

 the act of plundering a nest of F. suhsericea. I followed the cocoon- 

 laden workers a distance of about seventy feet to their nest, which was 

 on a sunny slope under two large stones. On removing these many 

 fine female pupae were found in the galleries and were carefully trans- 

 ferred to an artificial nest, where they soon began to hatch. The 

 young females were abundantly fed with sugar, houseflies, etc., and 

 were not used for the experiments till fully mature. In all twenty- 

 one experiments w^re performed. These may be divided into three 

 groups: nine were failures, two were partially and the remaining ten 

 completely successful. Two thirds of these experiments are given be- 

 low for the sake of emphasizing the typical reactions of the female ru- 

 hicunda. It is most improbable that this insect would respond to an 

 artificial environment with such a regular series of reactions unless 

 these are the very ones she habitually displays while establishing her 

 colonies in a state of nature. 



Experiment 28. July 13. At 2.15 p.m. a ruhicunda female was introduced 

 to 1 7 suhsericea workers with worker pupae taken from a wild colony of average 

 size. They at once fell upon her, four and six at a time, and succeeded in kill- 

 ing her by 3 p.m. 



Experiment 29. July 14, 7.30 a. m. a female ruhicunda was placed with 

 12 suhsericea workers and about 150 worker cocoons. She was immediately 

 attacked by several of the workers and dragged about the nest on her back. 

 Often the suhsericea were so excited that they kept tugging at a leg or antenna 

 of one of their own sisters that happened to be pulling one of the female's legs. 

 The female was singularly passive, but was finally so thoroughly aroused by 

 the pulling and tweaking that she killed three of the workers by 12 m. In 

 these struggles she lost one antenna and died at 2 p.m. 



