332 Mr. Newport on the Natural History 



characterized in the Transactions of this Society as the " Strepsiptera," from 

 the twisted form of the rudimentary elytra with which the male individuals 

 are furnished. Rossi's insect had in the meantime been examined by Pro- 

 fessor Jurine, who distinguished it from another species, also found in the 

 wasps. Mr. Kirby and Dr. Leach afterwards each described additional spe- 

 cies, Stylops tenuicornis and Stylops Kirbii ; and Mr. Curtis and Mr, Dale 

 each characterized a new genus, Elenchus and Halictophagus. These were 

 followed by new species by Mr. G. R. Gray, Stylops Childreni ; by Mr. Picker- 

 ing, Stylops Spencii ; by Messrs. Templeton and Westwood, Elenchus Temple- 

 tonii ; and by Leon Dufour, Xenos sphecidarum, — the whole of which were 

 found to be parasitical in their habits. Yet none of these naturalists were 

 able to ascertain anything perfectly conclusive respecting tlie sex of the 

 species they had captured. Professor Peck had however suspected that the 

 four specimens of Xenos obtained by himself were males ; although Rossi 

 imagined that the winged specimens which he obtained were of both sexes. 

 From what is now known we are satisfied that this was an error. It has been 

 well ascertained by Dr. Siebold that the male sex only is winged. This fact 

 established, raised at once a difficulty in understanding in what way these 

 insects are propagated, and by what means the females are brought into 

 communication with the species of bee or wasp on which they are parasites. 

 M. Klug, in 1810*, appears to have been the first to observe a fact that has 

 since led the way to an explanation of this problem in their natural history. 

 He remarked that the Strepsiptera are sometimes covered with little hexa- 

 pods, which he regarded as parasites. 



In December 1834, Mr. Pickering, in this country, obtained from its nidusf 

 in a sand-bank a living specimen of Andrena tibialis, which had recently 

 assumed the imago state, and had never left its cell. In this specimen he 

 " observed some protuberances between the abdominal segments, and think- 

 ing the bee might be stylopized, endeavoured to remove one of these swell- 

 ings," out of which be obtained a living (male) Stylops (Stylops Spencii), 

 which, like the insect it infested, had recently become perfect. This fact, as 



* Nachricht von einen neuen Schmarotzer insekt auf einer Andrene. Magazin der Gesellschaft 

 naturforschender Freunde zu Berlin, 1810, p. 266. 



t Trans. Entom. Soc. Lond. (Proceedings, Jan. 5, 1835), vol. i. p. 164. 



