REVISION OF STKEPSIPTEKA — PIERCE. 29 



icanus) crinitus, says these wasps, which are active and belligerent, 

 when overburdened with parasites "were lacking in vitalit} r , and 

 appeared to be on the sick list, as they rarely left the shelter of 

 the nest." Brues (1903) states that the infested Polistes annularis 

 are not as active as normal individuals but are often seen feeding at 

 flowers. Mr. Dury on August 24, 1905, took a female Polistes pallipes 

 so laden with parasites that it could hardly move. It contained 

 9 male pupae. 



Although these observations show a great loss of vitality, it must 

 not be supposed that death occurs quickly in all cases. There are 

 two periods in the biology of the parasites which are particularly 

 grievous to the hosts. One is the period of hatching, when the 

 triungulinids are crawling all over the body of the maternal host; 

 and the other is the period of activity of the male, striving to release 

 itself from its enshrouding envelopes. On a preceding page it has 

 been shown that individuals of Polistes annularis lived between 

 thirteen and sixteen days after the exit of males from their bodies 

 and also were found hibernating thus. Brues (1905) found seven 

 P. annularis in the field with empty puparia. Mr. Dury has kept 

 P. pallipes as long as twenty-one days after the emergence of the 

 parasites. On July 19, 1906 Messrs. Bishopp and Jones took a 

 Polistes rubiginosus with six empty puparia. 



It is well known that bees usually travel great distances in search 

 of the flowers they are accustomed to visit, the localities convenient 

 for nesting seldom being in close proximity to the flowers. Hence 

 it may be seen that the bees bearing parasites must often have 

 considerable vitality remaining in order to visit the flowers, for in 

 going to and from the flowers they must at one time or the other 

 fly in the face of the wind. When heavily laden with a parasite 

 this would be a rather difficult undertaking. It may be possible 

 that parasitized bees do not return to the vicinity of the nests at 

 night, but remain near the flowers. All parasitized bees taken in 

 North America up to the present time and known to the author 

 have been taken at flowers. 



In the study of the parasitism of Andrena crawfordi, Mr. Crawford 

 and the writer have made very close observations on all points 

 possible. A diligent search for the nests of this species was made 

 without avail. During April and May this bee is the most common 

 species of the Andrenine bees and the flowers it frequents are the 

 predominant flowers at Dallas, Tex. In past studies it has been 

 found by them that dominant bees generally nest in communities 

 or semi-communities — that is, that the nests are close enough together 

 to be remarked. So far, in spite of very frequent excursions with 

 this object in view no such conditions could be found. The effort was 

 made to ascertain the direction of flight, but this led to nothing. 



