INTRODUCTION cli 



characters of the male, the wings being more or less distorted in this sex by a special 

 clothing of the under-surface, which in 5. goviphias has the appearance of a dense felt. 

 Nesochlide has a group of specially modified scales on the underside of the forewings 

 in the male. The great Acrodrepanis and small Tritocleis lack the modified hind tibiae 

 and the characteristic hair-pencils of the other forms. 



Some of the species of Scotoiythra are amongst the commonest of moths, and 

 some have been able to adapt themselves to great changes in their environment. Thus' 

 Scoto7yth7-a rara and h'achytarsa sometimes become very numerous, their caterpillars 

 feeding on the introduced guava trees, in localities whence all native vegetation has 

 disappeared. We have even found caterpillars of this genus feeding on the strong- 

 scented imported Lantana. Sisyrophyta gomphias can also maintain itself away from 

 native vegetation. 



Many of the species of Scotorythra are polyphagous, but even these seem specially 

 to favour certain plants. Acacia koa is attacked by numerous species, and certain of 

 these become locally and periodically so numerous, that great areas of ' Koa ' forest are 

 entirely denuded of their phyllodes. When this denudation is long continued we have 

 known trees to be entirely killed, not perhaps altogether directly owing to the attacks 

 of the Scotorythra, but because, after a sickly condition had been induced by the 

 denudation of foliage, other insects (e.g. the longicorn beetles of the genus Plogithmysus 

 and the small, boring Scolytidae) joined in the attack. Scotorythra idolias on Hawaii 

 and 5". pahidicola on Maui were responsible for two of the most severe attacks that we 

 have witnessed. Native birds attracted in thousands by the abundance of this, one of 

 their favourite foods, were gorged to repletion, and the starving caterpillars formed 

 writhing masses on the ground beneath the tall Koa trees. The dropping of excrement 

 from the trees on the dead leaves beneath made a rattling noise as of a hailstorm. In 

 one instance it was noted that these pests of caterpillars were destroyed by an epidemic 

 fungous disease, which attacked the full-grown larvae after their descent to the ground 

 for pupation, as well as the pupae themselves. 



In open spaces in the forests at nightfall one may see large numbers of the moths 

 flying slowly overhead and often out of reach, traversing these spaces and all or nearly 

 all travelling in the same direction. Sometimes they congregate in hundreds within some 

 hollow tree-trunk or amongst the pendent masses of dead fronds of tree-ferns. In some 

 cases all the individuals so congregating are males, even in one case where several 

 hundreds of examples were taken together. Many of the species are attracted by light, 

 in some of these the males and in others the females are much more numerous. Thus 

 but one female of Nesochlide epixantha was attracted amongst scores of the other sex. 

 The males of this pretty species also freely visit the flowers of Metrosiderus, and they are 

 abroad on the most windy nights, to which, no doubt, is due the fact that one occasionally 

 meets with a strasgrler on the lowlands, and even in the town of Honolulu. The female 

 of this species is remarkable in that it is occasionally found flying freely in the sunshine. 



