306 HABITATIONS OF INSECTS. 



which it consists, interiorly it presents an arrangement admirably calculated 

 at once for protection against the excessive heat of the sun, and yet to 

 retain a due degree of genial warmth. It is wholly composed of numerous 

 small apartments of different sizes, communicating with each other by 

 means of galleries and arranged in separate stories, some very deep in the 

 earth, others a considerable height above it: the former for the reception 

 of the young in cold weather and at night, the latter adapted to their 

 use in the daytime. In forming these, the ants mix the earth excavated 

 from the bottom of the nest with the other materials of which the mount 

 consists, and thus give solidity to the whole. Besides the avenues which 

 join the apartments together, other galleries varying in dimensions commu- 

 nicate with the outside of the nest at the top of the mount. These open 

 doors would seem ill-calculated for precluding the admission of wet or of 

 nocturnal enemies : but the ants alter their dimensions continually accord- 

 ing to circumstances ; and they wholly close them at night, when all 

 gradually retire to the interior, and a few sentinels only are left to guard 

 the gates. On rainy days, too, they keep them shut, and when the sky is 

 cloudy open them partially.^ 



The habitations of these ants are much larger than those of any other 

 species in this country, and sometimes as big as a small haycock ; but 

 they are mere molehills when compared with the enormous mounds which 

 other species, apparently of the same family, but much larger, construct 

 in warmer climates. Malouet states, that in the forests of Guiana, he once 

 saw ant-hills which, though his companion would not suffer him to approach 

 nearer than forty paces for fear of his being devoured, seemed to him to 

 be fifteen or twenty feet high, and thirty or forty in diameter at the base, 

 assuming the form of a pyramid, truncated at one third of its height^ ; 

 and Stedman, when in Surinam, once passed ant-hills six feet high, and at 

 least one hundred feet in circumference.^ In the plains of Paraguay, 

 where the ants commit great devastations, a species described by Dobri- 

 zhofFer forms conical earthen nests three or more ells high, and as hard as 

 stone ; and in the Bungo forest in New South Wales, a very small ant 

 builds nests of indurated clay eight or ten feet high.'* 



The nest of Formica hrunnea is composed wholly of earth, and consists 

 of a great number of stories, sometimes not fewer than forty, twenty 

 below the level of the soil, and as many above, which last, following the 

 slope of the ant-hill, are concentric. Each story, separately examined, 

 exhibits cavities in the shape of saloons, narrower apartments, and long 

 galleries which preserve the communication between both. The arched 

 roofs of the most spacious rooms are supported by very thin walls, or 

 occasionally by small pillars and true buttresses ; some having only one 

 entrance from above, others a second communicate with the lower story. 

 The main galleries, of which in some places several meet in one large 

 saloon, communicating with other subterranean passages, which are often 

 carried to the distance of several feet from the hill. These insects work 

 chiefly after sunset. In building their nest they employ soft clay only, 

 scraped from its bottom when sufficiently moistened by a shower, which, 



' Huber, Recherches sur hs Maurs des Fuurmis, pp. 21 — 29. 



2 Ihid. p. 168. 3 stedman's Surinam, i. 169. 



* Westwood, Mod. Class, of Ins. ii. 223. 231. 



