Architecture in the Animal Kingdom. 107 



I found the spring nest deserted, I had only to look 

 where a given colony had passed the winter; there 

 they would be found under the clods of their nest. 

 Strange, you might say, to use one's winter quarters 

 as a summer resort ! Yet, on considering the shelter 

 afforded by a winter nest, situated in the brushwood 

 or at the roots of a shady tree, we may easily under- 

 stand that the very same place can protect ants both 

 against the cold of winter and against the scorching 

 heat of summer. In this winter and midsummer nest 

 the sanguineas generally stay during autumn and pre- 

 pare for their hibernation. Whilst the hill ants (F. 

 rufa and pratensis) are still busy building their hills 

 and setting out on expeditions to visit aphides, whilst 

 the small, black lawn ants (Tetramorium caespitum) , 

 the red stinging ants (Myrmica rubra) and the small, 

 brown garden ants (Lasius niger) are still in full 

 activity around their nests and are accompanying their 

 winged sexes on the way to their nuptial flight, there 

 prevails in the nests of sanguinea a quiet in striking 

 contrast with the feverish activity of the inhabitants 

 during the former months. The really active season 

 for F. sanguinea is from the middle of March to the 

 middle of August. Therefore their spring nests also 

 may be called working nests, whereas their winter 

 nests, which serve for midsummer and autumn, may 

 be called nests of repose. 



Besides these periodical changes of residence, F. san- 

 guinea will also incidentally move to another nest with- 

 in the temperate or hot season. This movmg is caused 

 by special conditions of the weather. If, on account 

 of long aridity and heat, the sanguine ants begin 



