Insects. 1147 



Of the genus Ccelioxys I am acquainted with four British species, 

 one of which, C. Vectis {Curtis), has been met with in the Isle of 

 Wight, where it is abundant ; it has also been taken at Little Hamp- 

 ton, in Sussex. I have no satisfactory evidence to prove on what bee 

 it is parasitic, but it has been taken in company with Megachile ma- 

 ritima, and probably is parasitic upon it. The typical species, the 

 Apis conica of Linnaeus, I have bred from the cocoons of Saropoda 

 bimaculata, and Mr. Waterhouse has reared it from those of Mega- 

 chile circumcincta. 



Mr. Kirby remarks that the males are usually without the addi- 

 tional abdominal segment, and subsequent authors have commented 

 upon this apparent peculiarity ; but on the careful examination of 

 recent specimens, it will be found that they have a seventh segment, 

 which is concealed, but easily drawn out. The examination of dried 

 specimens would lead to the incorrect inference mentioned above. 



Of the genus Stelis, two species have been discovered since the 

 publication of Mr. Kirby's Monograph ; and also the males of the two 

 described by him. In June, 1839, Mr. Thwaites bred a small species 

 of Stelis from a bramble-stick. It appears to be the S. minuta de- 

 scribed in the c Encyclopedic Methodique,' and also by St. Fargeau : 

 the specimen bred was a male. The bramble-stick out of which the 

 Stelis came, was procured from a locality where Osmia leucomelana 

 is abundant, so that the probability is, that it is parasitic upon that 

 insect. I recently captured a small Stelis in Hampshire, at a spot 

 where the same Osmia is abundant, and which I have no donbt is the 

 male of an insect previously described by me in this work (Zool. 261) 

 as a new species, also captured where Osmia leucomelana is abundant. 

 It is distinct from S. minuta, being larger, and more maculated with 

 white. I have on several occasions observed Stelis phceoptera enter 

 the burrows of Osmia hirta, and also of O. caerulescens. None of the 

 species are abundant, specimens being only occasionally met with. 



It will be observed that of those species which are parasitic upon 

 solitary bees, the males and females very closely resemble each other, 

 and differ little, or not at all, as regards either size or colouring ; as 

 in Nomada, Melecta, and the other genera here described. But the 

 discrepancy between the parasite and the bee is very great ; as in 

 Epeolus and Colletes, Nomada and the various species of Andrena : 

 the greatest resemblance obtains between Osmia and its parasite Ste- 

 lis, still, they are abundantly distinct. The history of this parasitic 

 connexion is still incomplete : it remains to be observed at what time 

 the egg or eggs of the parasite are deposited, and whether the bee 



