92 NATURAL RESOURCES SURVEY 



interesting observation. One somewhat windy day in Sept. 

 a hill was visited in which part of the ants were busily en- 

 gaged in bringing out the grain to air and others were as 

 busily engaged in carrying it back again. One ant would 

 drop a grain and at once start back without a load into the 

 hill for another, whereupon the grain would be at once seized 

 by another ant and carried back into the granary. It is pos- 

 sible that this treatment is what the grain needed but it 

 looked to the interested observer like a serious disagreement 

 in the colony as to where that grain should be, a case illus- 

 trating the limitations of instinct in developing "team work." 



Salius terminalis, Say. 



Scolia haematodes, Burm. 



DIPTERA 



Asilus exceedingly common and a good many species. 



Erax cinerascens, Bellard. 



E. varipus, Will. 



Promachus princeps, Will, common here and in all Sonoran. 



Ablantus sp. Are common from early March on. 



Anthrax alpha, O. S. Common. 



A. welistonii, Cog. 



A. fulviana, 0. S. 



Anastoechus nitidulus, Lee. Common and a favorite food 

 of the robber-flies. 



"Didges" are very abundant here. In May especially they 

 make life miserable for the traveller by their continual 

 asaults upon his eyes and ears. 



NEUROPTERA 



Brachynemurus ferox, Walk, and B. nigrilabris. Hag, are 

 common over the whole Sonoran. The pits of the larvae or 

 "ant lions" are common especially among the Pinons, but 

 the adults come in large numbers to lights at the University. 



Panorpa or "Scorpion-flies" have the same distribution but 

 are less common. These may not breed on the mesa. 



CENTIPEDIA AND ARACHNIDA. 



The following are characteristic of this and the next asso- 

 ciations. 



Scolopendra sp. These large centipedes are quite 

 common and frequently enter houses to the great dismay of 



