286 PROCEEDINGS OF TEE NATIONAL MUSEUM. vor,. 49. 



minute more it crawled farther up the stone, freeing the tip of the 

 abdomen, and continued to move about with nervous, jerky stc])s. 



At 9.55 it was twice the length and size of the skin, and the wings 

 had begun to lengthen. In the lengthening of the wings the bases 

 lengthened first and the tips last. The wings were then three- 

 fourths of an inch long, increasing in two minutes more to five-eighths, 

 and were clear except the costal margin beyond the nodus. All 

 during emergence the teneral rapidly and incessantly moved the 

 body up and down. At 9.59 the wings were 1 inch long, and in 

 another minute were clear. The abdomen during expansion of the 

 wings remained the same length as when first withdrawn, but at 

 10.04 it began to lengthen, the expansion beginning with the anterior 

 segments; at 10.09 the abdomen equaled the wings; at 10.12 it was 

 one-fourtli inch longer than the wings. At 10.15 the teneral, still 

 a grayish cream color, crawled nervously to the top of the stone and 

 flew weakly to a willow 30 feet distant. In two minutes after the 

 teneral had withdrawn its abdomen from the skin a hght gust of 

 wind had blown the skin into the water. The fact that most of the 

 larvae emerge on the riffles probably accounts for the few exuviae 

 found, as the stones there are round and smooth, permitting the skins 

 to be detached by the first puff of wind. 



The teneral stage probably lasts a day or two, during which the 

 insect avoids the opposite sex, and does not trust itself over the 

 surface of the water. Tenerals are usually found in the bushes 

 along the banks. 



I have never seen this species hanging in copulation, as is common 

 among Odonata. Its actions are so nervous and rapid that I am not 

 certain that I have ever seen it copulate. From my observation of 

 many pairs I think copulation is as follows: The male in flying about 

 and trying various females finally finds one in a receptive state. As 

 he swoops down on her she flies up, when he seizes her for a second by 

 the head or thorax with his feet, instantly throwing the tip of his 

 abdomen forward and seizing her by the prothorax. If he fills his 

 seminal vesicle during this process he does it the instant before he 

 seizes her prothorax with his abdomen.^ The very simple structure 

 of the accessory genitalia of segment 2 would indicate rapid action. 

 As the male releases the female from his first or foot grasp and 

 straightens Ms abdomen the female swings her abdomen forward and 



1 In my mind it is a question whether the male dragonfly necessarily fills his seminal vesicle while grasp- 

 ing the female. I have watched for the act of filling the seminal vesicle, but in several years collecting 

 have seen but one instance where I felt sure that I had seen the act. On Sept. 7, 1913, while collecting 

 on Satus Creek, I saw an Acalma (either palmata or umbrosa occidcnlalis) swoop at a female flying close 

 alongside a dense thicket and miss her. He then rose vertically a distance of about 12 feet to pass over the 

 thicket, during which rise ho had his abdomen bent forward with the ventrum of segment 9 attached to 

 segment 2. He was easily observed because of the dark liackground of foliage, and because, flying verti- 

 cally or " back first," he rose slowly. As he cleared the top of the thicket he straightened his abdomen 

 and speeded away. The whole process of filling the vesicle occupied less than three .seconds. 



