INTRODUCTION clxxxiii 



DoLiCHOPODiDAE. — The two species o{ Gnamptopsiloptis are no doubt introductions, 

 G. patellifer having been long established, and it is one of the commonest of flies. 

 G. pallidicornis is of recent introduction ; it was first noticed in 1896, was more 

 common in 1902 and is now still more frequently seen. Both are frequently bred from 

 soil in which young plants are being raised. On the other hand the species of Cafnpsi- 

 cnem is and Chrysotus are endemic, and no doubt many new ones remain to be collected, 

 as they are found throughout the forests, often in abundance. Unfortunately most of 

 the small and obscure Dolichopodidae have very soft integuments so that in a few days 

 or even hours after capture they become shrunken and distorted and almost useless for 

 descriptive purposes. They require special collecting and preserving, and it would be 

 safe to say that of this family at least 100 species might be procured in the 

 islands. Several species that frequent wet moss have the wings reduced to filaments 

 and are of course quite incapable of flight, but these interesting forms appear to shrivel 

 and distort after death and should be preserved in alcohol. Many of the smallest 

 species live on the ground beneath the shade of the trees, not only in wet but also in 

 dry forests, and if the dead leaves be swept aside and the damp earth exposed, they 

 are readily attracted thereto, and prey on the minute larvae of mycetophilids or other 

 delicate creatures, that are exposed amongst the disturbed humus. The little flightless 

 Emperoptera also has these habits, living in company with the small and equally active 

 Hemipteron, Nesidiorchestes, and other small insects, all flightless. The remark in the 

 systematic portion of this work that it was taken ' on Freycinetia ' is incorrect and no 

 doubt due to a wrong label having been attached to some of the specimens. It is 

 altogether terrestrial. Several commonplace Dolichopodidae found in and around Hono- 

 lulu are probably foreign {^Medeterus sp. ? &c.). 



PiPUNCULiDAE. — About a dozen species of the genus Pipuncuhis are already known 

 and probably numerous additional ones remain to be discovered. These species are 

 difficult to discriminate being mostly closely allied to one another, and some of them 

 apparently vary very greatly in size, perhaps in accordance with that of their host. 

 Several, that have been bred, are all parasitic on Delplacid leaf-hoppers, chiefly those of 

 the genus Nesosydne. The one species P. rotundipennis belongs to a different section 

 of the genus from that, in which all the others are placed, and its host is not known. 



Owing to the habits of the leaf-hoppers affected, most of the Hawaiian Pipunculus 

 are to be found flying round ferns or forest trees and shrubs, since most of their hosts 

 are to be found on these. They are never to be swept from grass, as is so often the 

 case in other countries. At least two species attack the common hopper of the Ipomoea 

 (^Nesosydne ipovioeicold) and are found flying round Convolvulaceous plants, on which 

 the host is so often found. Though all the species of Pipmiculus are certainly endemic, 

 yet two of them have attacked the introduced leaf-hopper of the sugar cane {^Perkinsiella 

 saccharicidd) which is widely separated generically from the endemic hoppers. Most 



