1S87. 83 



It is, of course, not impossible that Nomada, like Psitliyrus, may 

 hibernate as an imago, although probably ere this some one would 

 have found it in its winter quarters. If, however (as I believe is 

 generally thought), the species of Halictus hibernate in the original 

 burrows in which they reached maturity, there would seem to be no 

 reason why the larvae of Nomada should not remain in the full-fed 

 state through the winter, passing through their final stages in the 

 following spring, and emerging with the spring females of Halictus. 



A careful examinatioji of the burrows during the winter in 

 colonies where the inquilines occur alone could prove this, and I hope 

 Mr. Perkins himself will be able to make the necessary investigations. 



Nomada is peculiar among the inquiline genera in one very striking 

 particular, namely, the complete dissimilarity which it bears to the 

 genera with which it associates. Nearly all the other genera resemble 

 their hosts very closely in structure, and so remarkable in some cases 

 is this resemblance, that it is thought by some, and certainly with a 

 great deal of apparent probability, that the inquilines have only 

 become structurally differentiated from their hosts by a gradual 

 divergence of habit. 



Nomada is known to associate with SaUctus, Andrena, Panurgus, 

 and Eucera in this country, but to none of these does it bear the 

 slightest resemblance; in fact, its elegant shape, and the wasp-like 

 colours of most of the species distinguish it at once from any other 

 genus of the Anthophila. Professor Perez ably and carefully traces 

 its structural relationship to Megachile, but on what principle it should 

 have dissociated itself from its long-tongued allies, and associated 

 itself with species of the short-tongued division is hard to see : 

 possibly, its bright colours having made it an object of attack, it was 

 unable to resist the stinging powers of the Apidcs, and was driven to 

 the AndrenidcB, whose stinging powers are particularly feeble ; but, 

 if this be so, one has to seek for an explanation of the association of 

 Nomada fi-fasciata and Eucera ; or it is possible that the wasp-like 

 colours of the species make them objects of terror, except to those 

 genera of Apidce, which know their own superior strength. The only 

 other association which we have between long- and short-tongued 

 genera is that between Collefes and Epeolus ; and it is worthy of 

 notice that the species of both these genera sting with peculiar 

 virulence. 



St. Ann's, Mason's Hill, 



Bromley, Kent : 

 May 23rd, 1887. 



