xliv FAUNA HAWAIIENSIS 



flight, and clearly natural immigrants. Excluding these, the number of immigrants is 

 probably very small, for reasons hereafter given. 



Whereas the imported species are in most respects of little interest as compared 

 with the immigrant and endemic, in one particular they are of considerable importance, 

 especially such species as have been established in the islands for many years. House- 

 hold pests, however, and some others, that we know have been imported again and 

 again, are of no interest. It is probable that such introduced species as the Longicorn 

 beetles Laoocheirus obsolehts and Astrvnus hirtus were established from a single 

 importation of these species. They are evidently not frequently carried by man, for 

 until recent years the former had not spread to the other islands and the latter has not, 

 as far as is known, yet reached them. Yet the former is known to have become so 

 plentiful, as to have been an injurious insect in Honolulu forty or fifty years ago, and 

 the latter has been established at least for thirty years. Though for all these years 

 inter-island traffic has been very heavy, and plants continually taken from one island, to 

 another, and especially from Honolulu, where these beetles are common, yet the spread 

 o{ Lagocheirus has been slow, and that oi Astrimus has not, so far as is known, occurred 

 at all, as stated above. It is, therefore, very unlikely that either of these beetles has 

 frequently or even occasionally been brought to the islands from outside countries, 

 seeing that the traffic between these and Honolulu has been, until recently, compara- 

 tively very infrequent. I suspect, too, that these beetles are likely to be more abundant 

 with us than in their native countries. Owing to the equability of the climate, on 

 account of which so many insects breed the year round, and often produce many broods 

 in a year, many species have passed through very many generations since their intro- 

 duction. Some of the imported creatures we know from observation complete their 

 life-cycle in three weeks, and brood follows brood without cessation. Yet, when we 

 examine examples of these species, we may well feel some astonishment at the fact that 

 they quite resemble those found in their original home, even though this differs greatly 

 in climate and otherwise, and they exhibit no particular variability. Some (e.g. certain 

 Coccinellidae) notably variable in their native homes, appear to exhibit even less 

 variation here than in their own country. Looking at the imported species as a whole, 

 we must allow that these show no tendency to special variation, and there is not the 

 least reason to suppose that the variability seen is greater than, or different from that, 

 which they exhibit in their native homes. One is struck with the stability of specific 

 characters, and a study of these imported insects as yet throws no light on the question 

 as to whether variation arises suddenly or by slow degrees in a species. One would 

 infer that much time is as a rule required for the appreciable modification of a stable 

 species. 



The immigrant species are of two classes like the introduced ones: (i) those that 

 are, doubtless, more or less frequent \m^m\<gvA.x\\.s i^Pyrameis xar-diii, Nomophila noctuella, 

 large dragon flies etc.) and (2) those which are chance immigrants, of which no second 



