MEGACHTLB. 275 



Rose aud of the Laburnum, but the M, marilima seems 

 to prefer the leaves of the Sallow. The M. circumcincta 

 invariably burrows in banks, confirming the semi-grega- 

 rious habits of the genus, where it forms large colonies, 

 and it is only by accident that it constructs secluded and 

 solitary nests; it also makes use of rose leaves for lining 

 its apartments. The insects are subject to the molesta- 

 tion of bee-parasites of the genus Ccelioxys, the C qua- 

 dridentata having been bred from the cells of this latter 

 species, — that parasite also frequenting the M. Willugh- 

 biella, and the C vectis is well known to infest the M. 

 maritima. Thus, it appears to be only the species of this 

 division with the dilated tarsi that are exposed to such 

 incursions, there being no record of parasites frequenting 

 the division in which the males have simple anterior tarsi. 

 Besides this bee-parasite, they are also subject to the 

 attacks of some dipterous insect, whose larvae destroy the 

 larvse of the Megachile. Much difficulty exists in separa- 

 ting the females of some of the species from each other ; 

 in others the specific character is sufficiently noticeable. 

 It is a singular concomitant that those males with the 

 dilated anterior tarsi have the apical joint of the flagel- 

 lum of the antennse considerably compressed and also 

 dilated laterally. 



The proceedings of these bees are very curious. Al- 

 though the tubes they usually form are long, they are so 

 constructed as not to branch far away from the exterior of 

 the material into which they bore, — sound or putrescent 

 wood or earth, or old mortar joining the bricks of walls, — 

 if in the second material, they usually follow the pu- 

 trescent vein, and their tunnel in every case is rarely 

 further than an inch or an inch and a half from the ex- 

 ternal surface. Both the sides of the tube, and the cells 



T 2 



