AMERICAN HYMENOPTERA. 293 



quite closely resemble those of the Allegheney mountains. I have 

 also specimens taken during last summer by Prof. Joseph Leidy, M. D., 

 in the Rocky mountains, near Fort Bridger, Wyoming Territory. 

 These insects, though closely resembling the Allegheney mountain 

 forms, are somewhat longer, and more nearly approach the ants found 

 in Fairmouut Park, Philadelphia. The latter do not raise mounds ; 

 the Rocky mountain insects are mound-makers. In all the above 

 cases a light, sandy soil is the natural habitat of the ants. 



means of Attack and Defense.— The worker and female ants 

 are provided each with a pair of curved mandibles (Fig. 12; 8, inside 

 or palm; 10, outside; 9, male mandible); irregu- 

 larly toothed on the inner edge, which are at- 

 tached to the lower part of the head and have 

 a horizontal articulation. The teeth are seven, 

 the outermost one being much the longest; there 

 are (counting inward), two large teeth, one small, 

 one large ; two small and one flat tooth on the 

 inner edge. These organs are the implements 



-, ,„ o jui of labor and the weapons of warfare. They are 



Fig. 12. — 8, mandible ... ^ 



of worker, inside view; plied with terrible earnestness and vast force. 

 10, same, outside; 9, The method of inflicting a wound, as observed 

 mandible of male. upon my own hand, is as follows: the mandibles 



clasp the finger, and while the feet hold firmly to the skin, are drawn 

 together over it. with a scraping motion. At the same time the ab- 

 domen is doubled under the body acting as a sort of lever which 

 being pressed downward against the skin, greatly increases the power 

 of the mandibles to tear and pull the object seized. But this is not 

 the chief purpose of this movement; for from the lower part of the 

 abdomen a jet of formic acid is thrown forward upon the surface ou 

 which the mandibles are working. As the teeth or "cogs" penetrate 

 the cuticle this acid produces a sharp, stinging pain, suggesting a 

 puncture by a red-hot needle. I could not see the jet of acid, as I 

 have seen it when issuing from the Carpenter Ant, but the taste and 

 odor as well as pain, showed its presence. 



The wound thus made, which is neither a bite nor a sting, but 

 something like a combination of the two, is quite serious to inferior 

 animals, and is very annoying to horses and cattle. It is suflficiently 

 formidable to human beings to make them cautious in all their ap- 

 proaches to the hills. When the creatures fasten upon the neck or 

 get under the clothing and unexpectedly bestow their " bite," the 



TRANS. AMER. ENT. SOC. VI. (39) DECEUBER 1877. 



