248 HABITATIONS OF INSECTS 
cell requires a store of honey and pollen, not to be collected but with 
long toil, and that a considerable interval must be spent in agglutinating 
the floors of each, it will be very obvious to you that the last egg in the 
last cell must be laid many days after the first. We are certain, therefore, 
that the first ege will become a grub, and consequently a perfect bee, 
many days before the last. What then becomes of it? you will ask. It 
is impossible that it should make its escape through eleven superin- 
cumbent cells without destroying the immature tenants; and it seems 
equally impossible that it should remain patiently in confinement below 
them until they are all disclosed. This dilemma our heaven-taught ar- 
chitect has provided against. With forethought never enough to be 
admired she Fis not constructed her tunnel with one opening only, but at 
the further end has pierced another orifice, a kind of back door, through 
which the insects produced by the first-laid eggs successively emerge into 
day. In fact, all the young bees, even the uppermost, go out by this road ; 
for, by an exquisite instinct, each grub, when about to become a pupa, 
places itself in its cell with its head downwards, and thus is necessitated, 
when arrived at its last state, to pierce its cell in this direction. * 
Ceratina albilabris of Spinola, who has given an interesting account of its 
manners, forms its cell upon the general plan of the bee just described, but, 
more economical of labour, chooses a branch of briar or bramble, in the pith 
of which she excavates a canal about a foot long, and one line, or some- 
times more in diameter, with from cight to twelve cells separated from 
each other by partitions of particles of pith glued together? ; and from the 
dead sticks of the same plants, in which they had formed their cells in a 
similar way, MM. Dufour and Perris have bred in the sandy district of the 
Landes in the south-west of France not fewer than twelve distinct species 
of wild bees and other Hymenoptera, namely, four species of Osmia, two 
of Ceratina, three of Odynerus, two of Solenius, and Trypowylon figulus, 
besides fifteen species of parasitic Hymenoptera of the genera Stelis, Pro- 
sopis, Ichneumon, Chrysis, &c., making in all twenty-seven species of Hymen- 
opterous insects obtained from this prolific habitat, for which, too, they were 
indebted for very rare insects, which they had never before met with.® 
Mr. Thwaites has been also very successful in obtaining Hymenoptera from 
this source, having bred from dead bramble sticks found near Bristol Hyleus 
annularis and a new species, Ceratina albilabris Sp. cyanea K., Osmia leuco- 
melana, Epipone levipes, Cemonus unicolor, Spilomena Troglodytes, a new 
species of T'rypoxylon, and an unascertained one of Cladius, besides seven 
species of parasitic Hymenoptera, including Stelis minula, Chrysis cyanea, 
Hedychrum auratum, Cryptus bellosus, and three other Ichneumonidae, in 
all, sixteen species. —Crabro tibialis, which M. Perris says is parasitic on 
Hymenoptera residing in bramble-sticks (Ann. Soc. Ent. de France, ix. 407.), 
has been also found in this habitat near Bristol by Thomas Lighton, Esq. 
Such are the curious habitations of the carpenter bees and their 
analogues. Next I shall introduce you to the not less interesting struc- 
tures of another group of bees, which carry on the trade of masons (Mega- 
chile muraria), building their solid houses solely of artificial stone. The 
first step of the mother bee is to fix upon a proper situation for the future 
1 Reaum. vi. 89—52. Mon. Ap, Angl. i, 189, Apis. **, «. 2. Bs 
2 Ann, du Mus. x. 236. 
8 Ann. Soc. Ent, de France, ix. 1— 638. 
