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 egg 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 has 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, 

 pjaces 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. x 



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 eight to twelve cells separated from 

 each other by partitions of particles of pith glued together 2 ; 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 Trypoxylon 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. 3 

 Mr. Thwaites has been also very successful in obtaining Hymenoptera from 

 this source, having bred from dead bramble sticks found near Bristol Hylceus 

 annularis and a new species, Ceratina albilabris Sp. cyanea K., Osmia leuco- 

 melana, Epipone levipes, Cemonus unicolor, Spilomena Troglodytes, a new 

 species of Trypoxylon, and an unascertained one of Cladius, besides seven 

 species of parasitic Hymenoptera, including Stelis minula, Chrysis cyanea y 

 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 Lighten, 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 



> Reaum. vi. 39 52. Man. Ap. Angl i. 189. Apis. **. . 2. . 



2 Ann. du Mus. x. 236. 



5 Ann. Soc. Ent. de France, ix. 1 53. 



