INTRODUCTION cxxv 



Proterhinidae. — This family, excepting for a single species, which inhabits Samoa, 

 is at present only known from the Hawaiian group. Here about 130 species have 

 been recognized, and these form an assemblage exhibiting great variety of structure. 

 The discrimination of the species is a matter of very great difficulty owing to the 

 variability of many of them, and which are true species and which mere local forms or 

 varieties is very incompletely understood. It is quite certain that many of the species 

 apart from great variability in examples taken in the same locality, also exhibit local 

 variation, and further some are known to vary according to the nature of the food- 

 plant. There is often great variability in the size of the individuals of a species, and 

 concomitantly with this, the structural characters become modified. Some of the species 

 are polyphagous, feeding in the dead bark of widely different trees. Thus P. vestitus, 

 which may be considered the type of the genus, is found on the Kukui, Aletn-ites 

 (Euphorbiaceae), o\\ Pipturus (Urticaceae), on Charpentiera (Amarantaceae), etc. This 

 species does not show any particular variation in accordance with the food-plant. Other 

 species, on the contrary, such as P. oscillans and P. laticollis, are attached only to one 

 species of tree, those just mentioned breeding only on Acacia koa. Stragglers may be 

 found accidentally on other plants, having become dislodged from their proper habitat ; 

 and even at some distance, when, after high winds, by which branches or twigs are 

 detached and carried to a distance, the beetles leave these in search of a proper breeding- 

 place. Several species, e.g. P. longtihis, are found only on tree-ferns, while P. pteridis 

 is attached to Pteris and P. s/iarpi to an undetermined, but not arboreal, fern. A few 

 species leave the stems to feed on growing leaves of the trees they affect, and some 

 form burrows in the leaf stalks. Many of the species are gregarious and it is a 

 common occurrence to find a dozen or even many more individuals resting side by side 

 beneath dead bark. Sometimes quite different species are associated together in these 

 flocks. The apodous larvae are often found feeding in the bark, beneath which the 

 adults congregate, but some enter the solid wood of hard trees, while some breed in 

 the leaf-stems of ferns. Proterhinus is ubiquitous throughout Hawaiian forests, where 

 any native Coleopterous fauna remains, and ranges above these to a height of 9000 ft. 

 or more on the higher mountains, affecting the shrubs that grow at high elevations. 

 They entirely cease to exist in the lower forests, where these are well occupied by the 

 ant Plicidole megaccphala, which rapidly exterminates them. Doubtless, there has once 

 been a considerable number of species, inhabiting areas at lower elevations, which are 

 now extinct. Not a single species is now known from the coastal region of the islands, 

 though the Samoan species was found in coconuts, that had been grown on the coast, 

 in that group. It is probable that numerous species remain to be discovered outside 

 the Hawaiian islands, and possibly some forms will be found connecting Protcrhimts 

 more closely with the New Zealand Aglycydercs. 



Apart from size, colour and clothing, the variation that has been noticed to exist 

 in individuals of colonies of Proterhinus affects the size of the eyes, length of antennal 



