THE MOUND OF POGONOMYKMEX BAD1US LATKL. 165 



pose ; however, several months careful study has convinced me 

 that one of the most important functions of this mound is to serve 

 as a device to promote sexual union. The following description 

 of the behavior of this species, during the process of mating, will 

 make this point clear. 



Mating takes place, at intervals, during the warm weather. 

 How often this occurs and whether the intervals are regular or 

 irregular I am not prepared to say. I observed the inmates of 

 one set of nests mate on June 8 and again on June 16, and, on 

 several other occasions, I saw what looked like signs of recent 

 mating. Practically all the nests of the same locality mate at 

 the same time. On one mating occasion, out of eleven nests 

 occurring within a radius of a few yards, the inmates of eight 

 were going through the mating behavior. The three colonies 

 that were not mating were small and weak. 



During the daylight hours, a few workers usually promenade 

 on top of the mound ; just before a mating is to occur, this 

 number is increased many fold. To a casual observer, it looks 

 as though the majority of the inmates of the nest were out for a 

 sun bath. All move about in a nervous manner. A few males 

 and a few unfertilized (winged) females repeatedly emerge from 

 the nest, move about for a few moments, and then retire. After 

 this has continued for a time, the males fly away and the females 

 promenade among the restless workers. When the males arrive 

 at another mound, they alight and move about, in a jerky, 

 nervous manner, among the restless workers and females on the 

 mound. If, in its zigzag rushing, the male comes in contact 

 with one or more workers, these neuters attack it at once. Some- 

 times a male attempts to enter the nest. It is at once opposed 

 by the workers. I have never seen a male succeed in entering 

 the nest ; but, I think they do sometimes ; for, on more than 

 one occasion, I have seen workers dragging males out of the 

 nest. When a male comes in contact with a winged female, he 

 mounts her back and attaches his reproductive organs to the tip 

 of her abdomen. She either remains quiet, or else gently nibbles 

 the abdomen of the male with her jaws. After a few minutes 

 of intimate contact, the ants separate ; each to repeat the act 

 with some other ant. This coition always occurs either on the 

 ground or on a blade of grass or a low weed ; never in the air. 



