1907.] 



Wheeler, Fungus-growing Ants of North America. 



745 



"cat-claw," and had completely defoliated some of the bushes (Figs. IS and 

 19). Other colonies were carrying in the small leathery leaves and yellow 

 flowers of the grease-wood. Considerable quantities of these leaves had often 

 been gathered and dropped along the path or on the craters, as shown in Fig. 

 18, and left to wither in the sun when the ants withdrew into their nests dur- 

 ing the night or early morning hours. 



The colonies were much smaller than those of Atta tcxcina, although they 



Fig. 19. Acacia bush defoliated by Attu (Mwlterius) vcrsicoUir at Tucson, .\iizona. 

 graph by tlie author.) 



(Plioto- 



comprised several hundred workers. These varied considerably in size, 

 especially at Yucca. Dr. William Cannon, director of the Desert Lal)ora- 

 tory, kindly assisted me in excavating one of the nests which had only a single 

 crater. The entrance gallery, about 2 cm. in diameter broke up into a 

 number of small anastomosing galleries just beneath the surface and the.se 

 reunited to form a single gallery extending down into coarse, friable sand to 

 a depth of about a meter and terminating in a single small chamber wliicli 

 contained a fungus garden about the size of a walnut. This garden was 



