16 WASP STUDIES AFIELD 



but there were more of the vertical emergence-holes from 

 which newcomers had probably issued. 



It was soon apparent that there were more females pres- 

 ent than on the previous morning. There was a noticeable 

 reduction in the rivalry when a mating took place. A dozen 

 or more matings occurred in the low flight near to the 

 ground; since there was less rivalry, there was less need of 

 a quick escape, and mating could go on with impunity. In 

 only two cases was there marked rivalry where the mated 

 pairs were knocked to the ground, but instead of the teem- 

 ing mass of competitors which we had seen the day before 

 there were only three or four pursuers. 



The duration of copulation is brief. The time is hard 

 to estimate, but it usually continues through about fifty 

 feet of flight. The females are polyandrous, and all indica- 

 tions are that the males are polygamous. One certain fe- 

 male, which we could easily follow on account of her ex- 

 ceptional color, mated six times in a brief period. We are 

 sure, from close observation, that all of these were cases 

 of actual matings. In each case also the mating was spon- 

 taneous, that is the female was not coerced by the eagerness 

 of the males to mate, nor did the rivalry of the males cause 

 the separation. Each time, after the union had been ef- 

 fected, the pair glided near the ground for the usual dis- 

 tance of about fifty feet and separated ; the female returned 

 at once to the dance and whirled in and out until she casually 

 picked up another partner when the performance was re- 

 peated exactly. Thus with more females in the field on 

 the second day the rivalry was much reduced, and we saw 

 none of the extreme behavior of the males. 



This also points to the habit of priority of emergence of 

 the males, as we know occurs in other insects (cf. Sat- 

 urniids 2 ). 



2 Rau, Trans. Acad. Sci. St. Louis 23: 1-78. 1914. 



