Colour- groups of the Hawaiian Wasps, etc. 697 



to be seen nowadays. There were only a few species of 

 Lepidoptera, mostly Pyralids and Micros., and the wasps, 

 which necessarily came later than these, had no such field 

 for securing food as at present. If the Miillerian theory 

 is correct for these Hawaiian Hymenoptera, then the 

 separation of the Colour-groups began and was developed 

 gradually in past ages and the efficient causes are not 

 observable now. 



I stick out absolutely for the formation of all the genera 

 of Drepanid birds within the islands — and what a time it 

 must have taken to produce the extraordinary variety of 

 forms, now seen in this exclusively Hawaiian family ! 

 Looking at the birds, one ceases to wonder at the hundreds 

 of species of peculiar Achatinellidae in shells ; at the fifty 

 odd species of bees (Nesoprosopis) with their wonderful 

 variety ; at the 100 or more Odynerus, so varied in 

 structure ; at the vast genera in various groups of beetles ; 

 the (doubtless) hundreds of existing and very varied 

 species of the fly genus Drosophila, etc. I doubt whether 

 any but a systematist could rightly appreciate this wonder- 

 ful fauna, or even a systematist who confined himself to a 

 special group. 



It has been a great advantage to me that I was able to 

 work out all the Hymenoptera, Orthoptera and Neuroptera, 

 a large part of the Coleoptera, practically all the Hemi- 

 ptera (after Kirkaldy) as well as having largely studied 

 many groups of the Lepidoptera and Diptera. Then I 

 made a very large and perfect collection of the birds and 

 wrote upon these also, made special studies in the land- 

 shells, and have a moderate knowledge of the Botany. 



Guppy, who wrote on the latter, could never have had 

 his ideas, if he had studied the insects ; and the conclusions 

 of specialists like Lord Walsingham, who monographed 

 the Micros., are in my opinion quite untenable (see p. 681). 



Nov. IS, 1911. 



If the Miillerian theory is true of the Hawaiian wasps, 

 what probably happened is this : — 



1. There was a very ancient immigrant Odynerus 



(? whence) which gave rise to the vast majority 

 of the forms now present. 



2. It was a black-bodied insect with 2 (or more) narrow- 



ish pale abdominal bands. 



3. The descendant species of this Odynerus may have 



