INTRODUCTION clxxv 



Psocidae or Psocoptera. 



The species of this family are numerous, and very imperfectly known. The 

 endemic forms appear all to belong to two types, each with numerous species, repre- 

 senting the genera Psocus and Elipsoctis. Many of the species are very variable 

 and also closely allied, and as they are fragile and often indifferently preserved, they 

 are difficult to study. They are common throughout the forests of all the islands, and 

 endemic species still occur near the coast in a few places. Of recent years great 

 numbers of foreign forms have been imported with living plants, so that these are now 

 found in every garden, and some, and probably many, of these have extended their 

 range into the forests, and invaded the habitats of the endemic species. No doubt the 

 existence of the native Psocids in the islands is very ancient, as they are well known 

 to form the prey of other endemic creatures, e.g. the representatives of the Hemipterous 

 family Eniesiidae. 



Odonata. 



The two foreign dragon-flies, Pantala fiavescens and Anax junms, are extremely 

 common insects, both being particularly abundant on the lowlands, and they range 

 throughout the islands. Tramea lacerata, though not a rare insect, has been much less 

 successful. It too is essentially an insect of the lowlands, or at least of low elevations. 



Anax sirenuus, superficially similar to A. Junius, but much larger, belongs rather 

 to the mountains, and may be found five or six thousand feet above sea-level. At 

 moderate elevations of 1500 to 2000 ft., both these species breed freely in the pools of 

 the mountain streams, and we have taken the male of the one attached to the female of 

 the other on several occasions. I captured three such pairs in the course of two days, 

 when collecting in the mountains near Waialua on Oahu. Owing to the peculiar 

 method of copulation in dragon-flies, it is not possible to say whether this truly took 

 place or not. Apart from size, these two species of Anax are quite distinct by other 

 characters. As might be supposed the endemic A. streniiiis is a very powerful flier, 

 and on big streams and in open country is difficult to catch. Where they breed in 

 small streams flowing down narrow gulches, or in pools in small ravines, as they 

 continually pass and repass in their flight up and down, they may be easily taken. 

 On the larger Wailuku river near Hilo, where they were abundant, they were easily 

 killed with small charges of dust shot, as they flew over the surface of the water. 



Nesogonia blackbitrtii, a somewhat remarkable endemic dragon-fly, occurs on all 

 the islands in the mountains. It is often observed in localities where very little water 

 is to be found. This is due to the fact that it breeds in the small temporary pools that 

 remain for a time after heavy rainfall, as well as in small and easily overlooked water- 

 holes, that are of a more permanent nature. We have sometimes seen it in large 



