INTRODUCTION Ixxix 



form.^ It is most nearly allied to the Hawaiian species of the N. longiceps group. 

 The Hawaiian N'esoprosopis form a very varied assemblage, tending to split up into 

 a number of genera or sub-genera. The superficial differences between such extremes 

 as N. crabronoides and N. paradoxica are extraordinary, but throughout the whole 

 series of forms the essential characters of the genital armature and seventh and eighth 

 ventral segments remain the same, and bear strong evidence to the taxonomic value 

 of these characters. 



The Nesoprosopis are almost the most ubiquitous of any Hawaiian insects. 

 They are found in the hottest and driest coastal regions, when vegetation springs 

 up after the rains, and in the mountains extend their range far above the forest line 

 to the limits of vegetation. Some of the species frequent the most different stations, 

 e.g. N. volatilis, which has been found on the hottest coasts and at all elevations 

 in the mountains to a height of 9000 ft. in the region of snow in winter time. Many 

 range from the coast to about 4000 or 5000 ft. above the sea, especially N. facilis 

 and allied species. Others are purely littoral or range but a short distance inland, 

 e.g. N. longiceps, blackbtn-ni, hilaris etc. The members of some of the groups, 

 however, confine themselves to similar stations. Thus the small or moderate-sized 

 short-faced species of the N. laticeps group are only found in more or less dense 

 forests, where there is much shade and constant dampness. The large forms with 

 punctate abdomen are also true forest insects. Some species exist in, and in fact 

 favour, the wettest and densest forests in the islands, where the ground is always 

 saturated with rains or in the condition of a bog. N. laticeps and N. satelles seem 

 to thrive in such situations. 



In their nesting habits there is considerable variety. On the coast or lowlands, 

 or where the soil is sufficiently dry or sandy in the mountains, many form their burrows 

 in the ground, often, however, availing themselves of the pith cavities of dry branches 

 or twigs. Those frequenting denser and wetter woods in the mountains, of necessity, 

 burrow in dead tree stems or in hollow branches. Some affect the hardest tree-trunks, 

 e.g. of Ohia {Metrosidenis), sandal-wood, Mamani {Sophora) and utilize, when they can, 

 the borings of xylophagous beetles. Trees like the Lobeliaceous Clernwntia, the 

 dead branches of which are hollow, and afford a fine protection against the damp, 

 are frequently colonized by the larger species, such as N. Juscipennis. Some ot the 

 species seem to be of solitary habits and are rarer, while others sometimes form 

 great colonies, whether in the ground (e.g. N. difficilis, facilis, and many others) 

 or in dead tree-trunks, hard or rotten (e.g. N. paradoxica, melanothrix, etc.). 



Being so widely distributed, naturally a very great variety of plants are visited 

 by the different species in search of honey and pollen. On the coast and lowlands, 

 foreign, immigrant plants are mostly visited. The chief of these are Sida, Waltheria, 

 Vitcx, Capparis, Scaevola and Tribulus. In the same situations, where the forest 

 trees do not extend to the lowlands, a few endemic plants are also visited such as 



