THE HARVESTING ANTS. 285 



have fallen to the ground but plucks them directly from the plants, 

 husks them and deposits the chaff on the kitchen middens at the 

 periphery of its low, rounded craters. My own observations, made in 

 the sand}- grounds about Jacksonville, Florida, confirm those of Mrs. 

 Treat, who failed to find any tendency on the part of this ant to cut 

 down the vegetation or to clear areas around its nests. P. badiits 

 differs from all the other known species of the genus in having highly 

 polymorphic workers. The huge-headed soldiers are not abundant in 

 the colonies and seem to be no more aggressive or pugnacious than the 

 intermediate and small workers. P. coinanchc, which is common in 

 the sandy post-oak woods about Austin and Milano, Texas, and in the 



tr .^pli 



^ ^ -". A-JfefeC 



FIG. 162. Incipient crater of Pogonomyrmex rugosus in patch of Astragalus 

 which the ants are beginning to cut down and clear away. natural size. 



( Original. ) 



alluvial bottoms of the Colorado River in the same region, and P. cali- 

 foniicus, which is abundant in sandy portions of the deserts of Texas, 

 New Mexico, Arizona and California, have very similar habits. The 

 latter is represented by several local varieties and subspecies. Both 

 species carefully close their nest entrances at night. The incipient 

 nests are crescentic or semilunar with the very oblique entrance on 



