HABITATIONS OF INSECTS. 



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.i 



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 con- 

 centric. Each story, separately examined, exhibits cavities 

 in the shape of saloons, narrower apartments, and long gal- 

 leries 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, 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 suffi- 

 ciently moistened by a shower, which, far from injuring, 

 consolidates and strengthens their architecture. Different 

 labourers convey small masses of this ductile material between 

 their mandibles, and with the same instrument they spread 

 and mould it to their will, the antennae accompanying every 

 movement. They render all firm by pressing the surface 

 lightly with their fore feet ; and however numerous the masses 

 of clay composing these walls, and though connected by no 

 glutinous material, they appear when finished one single layer 

 well united, consolidated, and smoothed. Having traced the 

 plan of their structure, by placing here and there the found- 

 ations of the pillars and partition-walls, they add successively 

 new portions ; and when the walls of a gallery or apartment, 

 which are half a line thick, are elevated about half an inch in 

 height, they join them by springing a flattish arch or roof 

 from one side to the other. Nothing can be a more interest- 

 ing spectacle than one of these cities while building. In one 

 place vertical walls form the outline, which communicate with 



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



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