270 HABITATIONS OF INSECTS. 



But however rude its outward appearance, and the articles of 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 apart- 

 ments of different sizes, communicating with each other by means of gal- 

 leries, 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 adopted 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 communicate with the out- 

 side 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 according to circumstances ; 

 and they wholly close them at night, when all gradually retire to the in- 

 terior, 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 

 i 



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 2 ; and Stedmaii, 

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

 hundred feet in circumference. 3 In the plains of Paraguay, where the ants 

 commit great devastations, a species described by DobrizhofFer 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 indu- 

 rated clay eight or ten feet high. 4 



The nest of Formica brunnea 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 communicating with the lower story. The main 

 galleries, of which in some places several meet in one large saloon, com- 

 municating 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," far from injuring, 



* Huber, Recherches sur les Mcsurs des Fourmis, pp. 21 29. 



2 Ibid. p. 168. 3 Stedman's Surinam, i. 169. 



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



