THE ENTOMOLOGIST. 307 



of the crowned gall of C. argentea) are kept in check by other 

 means, and there is yet much to be learned in the study of 

 the limited company of insects in various galls, and in the 

 way whereby the balance of power is maintained between 

 them, these researches being inductive to others in the com- 

 paratively unlimited companies of insects elsewhere, and 

 both leading to the knowledge of the mechanism which 

 adjusts the agencies of the human race. Spinola relates the 

 history of Osmia Gallarum, a bee that I have already mentioned 

 as having been reared from the gall of Cynips argentea. It 

 does, he says, no harm to the Cynips; but the lawful mistress 

 having forsaken her habitation, it goes in by the way she 

 came out ; and having enlarged the empty space within, 

 builds there from twelve to twenty-four huts, whose walls are 

 smooth within, and are of ground oak-leaves, made adhesive 

 by glutinous matter; and this substance closes the entrance 

 into the gall. Each chamber includes an egg : thence comes 

 the grub, which, as usual, is a pollen-eater; and having 

 changed into a bee, goes out by the door before used. 

 Perhaps Fcenus and Chrysis are agents in the second house- 

 hold, and not in the first, and do not direct their attention 

 to the galls till they are tenanted by the Osmia. Leucospis 

 intermedia has been also found in these galls, and may be a 

 parasite of the Osmia. But there are other events which may 

 happen in the domestic matters of this habitation. Supposing 

 that a parasitic egg has been inserted into the Cynips larva of 

 the central cell, before the latter has been surrounded by 

 ante-chambers, then the destroyer would perish with the 

 victim, — the M. giganteus would be immured with the 

 Cynips. Supposing, also, that some of the minor Chalcids 

 have visited the inquilines, then the nurseries of the latter 

 become their graves, out of which the offspring of the 

 Chalcids arise. The round hole in the gall is made by the 

 legal Cynips, and through this hole it comes out; but how 

 do the other kinds come out, and how are they introduced 

 while they are eggs ? The occupation by the Osmia indicates 

 that the aboriginal Cynips has been unmolested ; and it is 

 probable that the cuckoo-flies, before mentioned, take an 

 opportunity, when the Osmia is absent in search of materials 

 for constructing its cells, to secure a maintenance for their 

 own offspring. The Osmia, having assumed the bee- state, 



