MEGACHILE. 
275 
Rose and of the Laburnum, but the M. maritima 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 Cwlioxys, the C. qua - 
dridentata having been bred from the cells of this latter 
species,—that parasite also frequenting the M. Wil/ugh- 
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 larvie 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 antenme 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 die 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 
