INTRODUCTION cxlix 



a very large number of moths bred from caterpillars, that were injuring a fine hedge of 

 a foreign Hibiscus, showed no remarkable varieties. Sometimes the foliage of the 'Hau' 

 tree (//. ii/iacciis) is much injured by these caterpillars. C. noctivolans is sometimes 

 found commonly in dry places amongst Sida, on which the larvae feed, as well as on 

 some of the plants affected by C. sabiilifera. The latter is much parasitized by the 

 common Tachinid flies, Chaetogacdia and Frontina, so that hedges of Hibiscus, very 

 badly defoliated, may become entirely freed from caterpillars by their means. 



Of the two species of Hypocala, H. andremona is, doubtless, a natural immigrant, 

 these insects being endowed with great powers of flight. H. velans, considered by 

 Meyrick as a variety of andremona, is, I think, clearly a distinct species and presumably 

 derived from the latter. It appears to be much more numerous than andremona in most 

 parts of the islands. In the daytime it often secretes itself amongst the lava, which 

 is piled up to form walls in various parts of Hawaii, and from these it is very easily 

 disturbed in the daytime. It also frequents the caves and cavities in the sides of 

 precipitous gulches, issuing from these in great numbers, as we have noticed on Molokai 

 and elsewhere. It freely enters houses, much more often than H. andremona. Both 

 feed on Maba sandivichensis, and their earlier stages have been studied by Swezey, 

 confirming their distinctness. Although most abundant on the lowlands and lower 

 mountain slopes, we have noted the occurrence of H. velans in a well-known cave at 

 an altitude of nearly 9000 ft. on Haleakala. 



Plusia chalcites and P. biloba are, no doubt, natural immigrants, the former 

 ubiquitous and very numerous, often indeed injurious, being polyphagous, the latter 

 most partial to the uplands and generally scarce. P. chalcites occurs also on Midway 

 Island. In the wettest districts of the islands the caterpillars are sometimes destroyed 

 wholesale by epidemics of a fungous disease, while another fungus attacks the moth. 

 The pupae are much parasitized by the endemic EchthromorpJia and the imported 

 Chalcis obscurata, and the caterpillars by the Tachinid flies. But for these restraining 

 agents, P. chalcites would prove one of the worst of pests. P. pterylotis is a very remark- 

 able endemic species of rare occurrence, but widely distributed, as it has been found on 

 Oahu and Hawaii. It is replaced on Maui by an allied, but very distinct species. 

 These endemic forms have no connection with the apodemic ones named above, nor 

 are they apparently closely related to any known species of the genus. The cause of 

 their rarity is not known, but, no doubt, they will be found to be heavily parasitized by 

 the Echthromorpha, which is always very numerous in the localities where they occur. 



Hydriomenidae. — The greater number of the species belong to the genus 

 Eucymatoge, with 10 described forms and, doubtless, others to be discovered. 

 E. monticolans is ubiquitous throughout the forests, and is remarkable for its great 

 variability. Extreme varieties are often found in company, but in some localities 

 (notably, e.g., on the summit of the small island of Lanai) there is a tendency for some 



