clii FAUNA HAWAIIENSIS 



No doubt, formerly, numerous species have existed on the lowlands, but these have 

 mostly disappeared owing to the attacks of foreign predaceous insects, especially ants. 

 In very dry localities, where that destructive little ant Pheidole megacephala is unable 

 to exist, or is hardly present, species of Scotorythra still flourish. This is the case with 

 6'. paratactis, the caterpillars of which are very numerous on the scanty vegetation that 

 grows near the coast on the driest parts of the west side of Oahu. The exposed cater- 

 pillars of this species would be quickly exterminated by Pheidole in most parts of the 

 coastal region of this island. 



The caterpillars of some of the species of Scotorythra appear to be nocturnal in 

 their feeding habits, and during the daytime hide beneath the bark of the trunks of the 

 trees, on whose foliage they feed. In this situation considerable numbers may be found 

 at rest, ranged side by side. They form a most important j^art of the food supply of 

 the endemic birds, and are supplied by the parents to the young of nearly all the species, 

 while they are a favourite food of many adult birds as well. On the other hand they 

 are very little attacked by the many species of wasps of the genus Odyjierus, and it is 

 most remarkable that, since these do occasionally store them up in their cells as food 

 for their young, they should not more often avail themselves of so abundant a prey, 

 when more favourite caterpillars become scarce or fail. The ubiquitous bug, Oechalia 

 grisea, also destroys great numbers of the larvae of many Scotorythra. The variation 

 in colour and markings of many of the species of Scotorythra (as well as of Nesochlide 

 and Acrodrepanis) is very great, and some idea of this variability may be gathered 

 from the figures accompanying the systematic descriptions in this work. In most 

 species, that show much variation, the extreme varieties are taken in company. It is 

 not known whether difference in the food plant is to any extent the cause of variation, 

 but it is certain that it is not so in some cases, where variation is very great, as several 

 species have been tested in this respect. It is very noticeable how frequently species, 

 that are quite distinct, yield similar varieties, and a character which appears as a 

 variation in one or more species may be a constant character in another. As an 

 example of this one may mention the presence, as a constant character, or merely as 

 an infrequent variation, of a conspicuous pale costal streak. In some species the males 

 and in others the females appear to be more subject to variation, and some, of which 

 large numbers have been examined, exhibit very little variability. 



The pupae of Scotorythra are very commonly found when one is searching for 

 other insects, under wet moss, in damp rotten wood, under logs, and in other situations. 

 Most of them, however, as well as the caterpillars, are difficult to breed, when removed 

 from the wet mountain forests to the lowlands, even though great pains are taken to 

 keep them as nearly as possible under natural conditions. Some of the large species 

 have been observed laying their eggs in the bark of trees, the ovipositor being of great 

 length when fully protruded. 



