170 . The Ottawa Naturalist. [Dec. 



material may be used by the same species to construct their 

 "cow-sheds" or tents. 



As we concluded in our memoir, "There is no doubt that 

 this habit of building detritus and carton tents has developed 

 for no other purpose than that of protecting the various species 

 of aphides which are kept by the ants for the sake of their 

 honey -like secretions. By the construction of such "cow-sheds" 

 the aphides are able to continue sucking the juices of the plant 

 and at the same time they are not only protected from their 

 enemies, but also from alien ants. The protection from cold is 

 also important, as Brandes (in 'Die Blattlaus und der Honigbau,' 

 Zeitschrift f. Natur wiss, vol. 66, 1894), has found that aphides 

 are most active during the warmer part of the day, so that in 

 keeping these warm the ants v/ould also be obtaining a large 

 supply of the secretion from them. In addition to these explana- 

 tions of the tent -building habits of ants, Wheeler also suggests 

 that the tents may be to prevent the escape of the aphides to 

 other plants or other parts of the same plant. 



"The evolution of the forms of the tents which are found 

 in the different genera of tent-building ants may have started 

 with the small earthen cell covering a few aphides; this may 

 have been constructed either on the stem or by filling the space 

 formed by the inrolling of certain of the leaves. Further en- 

 largement and elaboration would lead to the formation of a 

 spherical or cylindrical tent having the stem as axis, and finally, 

 to secure for themiselves the greatest comfort and convenience, 

 the ants would connect these tents either with the earth or with 

 their subterranean nests by means of covered passages." 



This great adaptability to its environment, the usage of the 

 means at hand and variability of constructive power in a single 

 species of insect such as Lasius niger, is of very great interest to 

 the entomologist who becomes so accustomed to the fact of a 

 certain species of insect making nests or structures of a particular 

 and more or less fixed type, such as we find in the other social 

 and solitary hymenoptera as the bees and wasps, and also in 

 other orders of insects. 



BOOK REVIEW. 



Farm Weeds of Canada. Bv George H. Clark, B.S.A., and 

 James Fletcher, LL.D.. F.R.S.C, F.L.S., with illustrations 

 bv Norman, Griddle: Second Edition. Revised and En- 



