INTRODUCTION cl 



XXI 



the Hemerobiidae, one genus, Ncsomicrovms, of the Hemerobiinae, contains 22 known 

 species, Anonialochrysa of the Chrysopinae 29, Agrion of the Odonata 26, Psoais of 

 the Psocidae 14, and Elipsocus 10. No less than loi of the species of Neuroptera are 

 consequently distributed in only five genera ! 



Many families or even greater groups are totally unrepresented. Thus there are 

 no Trichoptera, Perlidae, or Ephemeridae of the aquatic groups, no Mantispidae, 

 Panorpidae, Ascalaphidae, etc., of the terrestrial forms. 



Hemerobiidae.^ — The single species referred to Megalo7mis is a rather common 

 forest insect throughout the islands, the habits of which are very imperfectly known. 

 It exhibits some rather remarkable variations, and though allied forms will, no doubt, 

 be found elsewhere, it may itself prove to be endemic. We have not seen species from 

 other countries having the same peculiarities of neuration, which will no doubt exclude 

 it from the genus Mega/onnts properly called. It flies at dusk and sometimes is 

 attracted by lights in the nighttime, hiding by day amongst dead leaves attached to 

 trees, and amongst dead fern-fronds. When beaten from these it feigns death like 

 others of the group. 



The species of Nesomicromus exhibit a great variety of appearance, some having 

 the remarkable contour of the wings of D repanopteryx, though of course not allied to 

 this, while others hardly differ from some species of Micromus, described from other 

 countries. The more remarkable forms appear to be related to and connected by 

 intermediates with the more commonplace ones. They are a difficult study, since 

 many are so rare as to have been very imperfectly examined, and the difficulty is 

 increased by the variability of the neuration and other characters. With the exception 

 of N. vagus, which occasionally ranges to the coast, all are forest insects, many of them, 

 as has been stated, rarely or very rarely collected. On the other hand N. vagus is 

 often met with in great numbers. Mostly they frequent trees or ferns infested with 

 Psocidae, on which they prey, but some, and especially those which are found most 

 numerously, attack Aphidae. Amongst the latter may be mentioned N. vagus, 

 minimus, and fulvescens. One is tempted to think that the greater abundance of such 

 species is due to this habit, the large number of Aphidae, which have become imported 

 with various plants, affording a more abundant pabulum. Probably Aphidae were 

 entirely absent from the endemic fauna. //. vagus, the most successful of all the 

 species, now sometimes abounds outside the forest in fields of sugar-cane attacked 

 by Aphis sacchari, on maize, etc., and in the mountains we have found it in enormous 

 numbers on the rare tree Gossypiwn drynarioides infested by Aphis gossypii. On one 

 occasion the capsules of the latter plant were found full of the cocoons of N. vagus, 

 the larvae having crept within for the purpose of pupation. If, as is probable, the 

 Aphidae were absent from the fauna until they were imported by man, it is most 

 likely that the Psocidae and small Homoptera previously supplied the sole food of 



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