THE MOUND OF POGONOMYRMEX RADIUS LATRL. 



AND ITS RELATION TO THE BREEDING 



HABITS OF THE SPECIES. 



C. H. TURNER. 



Even casual observers, visiting the suburbs of Augusta, Ga., 

 are sure to notice this ant ; not merely because of its large size, 

 but on account of its conspicuous mounds, which are scattered, 

 in open places, on all the vacant highlands. A somewhat dry, 

 sandy soil seems best suited for its development ; for, although 

 the mounds are numerous on the divide, both along the road- 

 side and in open patches in the woods ; yet, they are practically 

 absent from the low, damp flood-plain. The conspicuousness 

 of each mound is not due to its height, for each is only a few 

 inches high ; but to its large, barren surface. Some of the 

 mounds are as much as five feet in diameter, and many have a 

 major axis of three feet. The area of the mound seems to be a 

 function of the size of the colony. I say size rather than age of 

 the colony ; because an old, but weak, colony will often have a 

 smaller mound than a much younger colony that has a large 

 population. This condition of affairs is due to the habit of occa- 

 sionally abandoning its old mound and excavating a new one. 

 If the migration occurs when the colony is small, even though it 

 is old, the area of the mound will be small. In small mounds 

 the shape is often subcircular ; but in larger mounds the shape 

 departs much from that of a circle (Figs. I 8). This mound is 

 composed partly of materials excavated in forming and enlarging 

 the burrows and partly of small pebbles and other coarse ma- 

 terials collected from the surrounding surface of the ground. All 

 sizes of workers participate in making the mound. 



The number of openings into the nest varies from one to sev- 

 eral. This is true not only of different nests, but of the same 

 nest at different times. If an opening to a nest is closed with 

 small particles, by some agency foreign to the nest, the ants that 

 may be on the outside at the time act, for a time, as though they 



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