294 ' C. T. BRUES. 



extent account for the discrepancy between the two series of 

 observations. 



The presence of numbers of females in the wasps during Octo- 

 ber when Polistcs are searching for hibernating quarters suggests 

 that the parasites pass the winter in this state. With these species 

 as is known to be the case with Xenos pcckii, a cursory examina- 

 tion under the microscope showed that the masses of eggs in 

 several females were in a very early stage of development. From 

 this there seems no reason to doubt that the gravid females 

 hibernate in this state, and that the later embryonic development 

 is passed during the early part of the following spring. It would 

 appear very doubtful that any males hibernate. The fact that 

 many had emerged and that those still remaining in the pupal 

 envelopes had already acquired their adult color by October first 

 shows almost conclusively that all would emerge before winter. 

 Spring observations also support this idea for no males were seen 

 in over-wintered wasps. Neither were any wasps containing 

 empty male pupal cases seen in the spring. During the winter a 

 large proportion of the Polistcs die, and no doubt the ones from 

 which males had emerged would succumb first. In the nest in 

 question, then, only ten of the parasitized wasps could be expected 

 to survive the winter. That the majority of these die also is 

 shown by the scarcity of parasitized wasps in the spring. 



From these facts it is evident that no males survive the winter 

 and probable also that no wasps which have contained males sur- 

 vive. This necessitates the death of a large proportion of the 

 female- Xenos since it has been noted (ante, p. 292) that of 44 

 females only 14 were in wasps that did not contain males. 



On account of the difference of opinion as to the way in which 

 the wasps treat the emerging male parasites, a close watch was 

 made on several occasions, but at no time could it be observed 

 that the wasps took any notice at all of the fluttering male Xenos. 



Quite recently Pierce ('04) has added to our list a new species 

 of Stylopidae described by him as Xenos pulviiiipcs. An ex- 

 amination of his figures and description convince me that this 

 form is generically distinct from Xenos for several important 

 reasons. According to the description the female possesses 

 distinct eyes, a character at once distinguishing it from Xenos 



