36 Trans. Acad, of St. Louis 



a half dozen were at work, and Ijv July !."> all had disap- 

 poarod. This is a wator-carryin": boc. They came to a 

 l)ud(llo in a wairon-rnt about a hundrcil foot away for 

 water; when tliis dried np thoy readily lilK'(l their crops 

 from a dish of water placed on the <rronnd with floating 

 sticks in it for thorn to alight on. 



On the first of May 1921 a lot of cells containiniz; niatur- 

 in|i;' Anthophora ahrupta bees were brons^ht into the labor- 

 atory, and the sex and date of omero^once noted. The 

 males emerged over a period of sixteen days. May 10 to 

 May 25, and the females over a period of only three days. 

 May 23 to 25, or the time coincident with the last three 

 days of male emerp^once. With one male emerging: on 

 May 10, the number on each day followine: was 1, 2, 4, 

 1 ,2, 4, 5, 9, 84, 54, 30, 64, 8, 3 and 1, totalins: 273 males. 

 The females first appeared thirteen days later than the 

 first males, but 28 strong; 53 emerged on the next day, 

 and 20 on the last, or 101 in all. Hence the priority of 

 male emergence is here quite unmistakable. This fact is 

 frequently met in the insect world; it seems to be an 

 ingenious device of nature to eliminate a waste of the 

 time of the busy females when every summer day is 

 precious. 



In Saturniids a similar condition exists. In recording 

 the sex of nearly 3600 giant silk-worm moths as they 

 emerged from their cocoons, we found the ratio of the 

 sexes to be 111 males to 100 females, and the mean date 

 of emergence of the males was from one to five days 

 earlier than that of the females. 



Prosopis pyganeus Cress. [8. A. Kohwer]. Found in 

 a sumac twig in the park, in winter of 1919. 



Prosopis sayi Robt. [J. C. Crawford]. Two males 

 taken from a tunnel in a sumac stem at 7:30 \). n\. on 

 July 4, 1918. The burrow was only one-half inch deep, 

 and the insect had evidently crept in there to sleep. 



Prosopis cressoni [d. C. Crawford]. An elde]*^twig 

 taken at Wickcs, Mo., on June 28, gave forth three adults 



