IN TROD UC TION xcix 



The percentage of endemicity of species on the islands, exckiding Kauai, is, 

 as shown above, extremely close, and, as more new forms are likely to be found 

 on the other islands than on Oahu, this percentage may become still closer. 



Vespidae. — The three species of Polistes, two of them introductions from China, 

 viz. P. hebraeus and P. macaensis, and one from California, P. aitrifer, are all very 

 abundant insects. P. macaensis and aurifer were present in the islands more than 

 thirty years ago, but P. hebraeus is of later introduction and was not generally 

 distributed over the islands in 1892, nor did it reach Hawaii till some years later still. 

 Although treated as varieties by most authors, P. macaensis and hebraeus are quite 

 distinct by the different processes of the sixth ventral segment of the male abdomen. 

 The Polistes are now nearly ubiquitous, from the coast to six thousand or more feet 

 above the sea. On the central plateau of Hawaii I have noticed nests built in the 

 bleached skulls of cattle and sheep, that are thickly spread in some parts of that 

 desolate country. These wasps are beneficial in destroying numbers of harmful cater- 

 pillars, but are otherwise a nuisance. They are affected by the Stylopid parasite Xenos, 

 and the Pjralid moth, P. maziriiialis, breeds in the nests. 



Bethylid.ve. — The species of Scleroderma present feeble specific differences, so 

 that the number recorded (10) is subject to change, for little is known as to their 

 variability, etc. We have, however, noticed in bred examples of one species a very 

 decided individual variation in the shape of the propodeum, an important character. 

 Their habits are not well known. One or two species have been bred from dead wood, 

 yielding various beetles (Anobiidae, Cioidae, Cerambycidae, Proterhinidae) and Tineid 

 Lepidoptera mixed, and the possibility of other insects being represented, but failing to 

 emerge, is, of course, great. It is, however, known that one or two of our species 

 attack Microlepidoptera, so probably many have this habit. Male examples are very 

 rarely met with in the field and not often bred, so that it is probable that Scleroderma 

 like the apterous females of Dryinidae are often parthenogenetic. 



Sierola differs greatly from Scleroderma in the fact that while individuals of the 

 latter are not generally common, those of the first genus are quite the most plentiful of 

 the parasitic Microhymenoptera. They are essentially forest insects, though one or 

 two of them are occasionally found without the forest. Their habits are quite different 

 from those of Scleroderma, for they are commonly seen running on the leaves of the 

 ' Ki ' {Cordyline terminalis), of Pelea, Acacia koa and many other trees and shrubs. 

 They are parasitic on various caterpillars, but chiefly, I think, those of the Micro- 

 lepidoptera (Tineina and Tortricina) from which I have occasionally bred specimens, 

 but they also attack those of larger moths, for Swezey has bred S. dichroma from 

 the caterpillar of Oiuiodes asaphombra. A former remark of mine that Sierola was 

 parasitic on Cioidae is certainly incorrect, and it was, no doubt. Scleroderma and not 



