252 BRITISH ANTS. 



able and the same, rather than to send off swarms to less favour- 

 able localities. 



A number of tracks, or open streets, extend to some distance 

 from a nest Forel gives eighty to one hundred metres 36 ; these 

 tracks often lead to trees infested by Aphides, or some other hunt- 

 ing ground, and the ants sometimes cut down the vegetation to 

 clear a path. 



Bignell says " that a new colony within a hundred yards, 

 would, I feel certain, not be permitted by the old one " 58 , but 

 now that we know how rufa founds a new colony, as will be shown 

 later, it is clear that such a contingency would not arise. 



In 1880 he records what he took to be a raid by a large colony on 

 a smaller one two hundred feet away, the ants of the former carrying 

 those of the latter by the mandibles 41 , but this was certainly a case 

 of a branch nest, and no ant would allow a stranger to carry it 

 quietly away from its nest in the manner he describes ! 



On June 12th, 1911, I observed a branch nest of rufa in the 

 Black Wood at Rannoch. Two nests were found to be in connec- 

 tion one hundred and twenty-eight yards apart, one a large mound, 

 about seventy-two inches in diameter and fifty-four inches in 

 height, a few yards below the path, and the other a small hillock 

 about the same distance from the path on the other side of it. The 

 ants were going backwards and forwards along the path to the 

 two nests, food being carried to the large nest, but the ants were 

 carrying their larvae from the large nest to the smaller one. A 

 deflated female was trying to get to the smaller nest ; though often 

 stopped by the workers, she persisted and gradually won her way 

 to it. Some winged females were up on the top of the large mound 84 . 



Colonies of these ants comprise a very large number of individuals 

 for a single nest Farren- White suggests ten thousand 52 , and Forel 

 estimated (for a pratensis nest) ninety thousand to one hundred and 

 fifty thousand. Yung, who actually counted the inhabitants of five 

 rufa nests, gives for the one with the fewest ants a nest Om 45 high 

 and Om 95 in diameter, 47828, and for the one with the largest 

 number a nest Om 65 high and 1m 40 in diameter, 93694, and he 

 thinks, making all due allowances for possible errors, that a single 

 nest would not contain much over one hundred thousand ants 62 . 



Formica rufa secretes a large amount of Formic acid (HCOOH), 

 the Spiritus formicarum, and is the most capable of ejecting it 

 into the air in defence of the nest, etc. ; these ants partly paralyse 

 their prey with acid discharges, and spray the liquid into a wound 

 caused by their mandibles. When alarmed, or enraged, the workers 

 stand up on the tips of their feet, with the gaster bent between their 

 legs, and the acid is ejected to a considerable distance from the 

 anal aperture. Forel says it is shot into the air to a height of five 

 to six decimetres 37 , Daniell 19 and Conway 8 give six and three 

 inches respectively, but they both inaccurately state it is ejected 



