412 NATURAL HISTORY OF HAWAII. 



way to a field of fascinating and practical study tliat others, not wholly con- 

 sumed with the desire to add new species to the fauna, nor equipped for serious 

 systematic research, will find of value and interest. 



During a period of two or three years in connection with other fiekl col- 

 lecting, mostly confined to the Island of Oahu, he gathered and studied mate- 

 rial from which he reports the taking of more than seventy-five insects and 

 their parasites from this single species of plant. He enumerates nine species 

 that appear to be found on mamaki and on no other plant. Thirteen species 

 feed extensively on its leaves, one bores into the green twigs and one lives on 

 the bark. Of those attacking the dead or dying shrub, eighteen occurred in 

 the trunk and branches, and two feed on fungus, on or beneath the bark. The 

 insects which visit mamaki in search of prey w^ere divided into five species of 

 Coleoptera, four species of Heyniptera, eight parasties besides other miscel- 

 laneous insects, as ants, earwigs and rove beetles. 



The problems of insect life are so interesting and so varied in Hawaii tliat 

 the repetition of the investigation referred to above would well repay any 

 observer on Oahu, while the insect fauna varies to such an extent on the dif- 

 ferent islands that the work, if repeated on Hawaii or Kauai, for example, 

 would have all the novelty of original research. 



Some of the more minute and scarcer groups of Hawaiian insects have not 

 as yet been systematically studied. The larger and more important orders 

 that have been reviewed l)y specialists are constantly having new genera and 

 species added to them as a I'esult of more detailed study. This makes general- 

 izations based on the data available less accurate than one could wish. Never- 

 theless, some of the main facts selected for a popular resume of the orders as 

 discussed in the Fauna Hawaiiensis, supplemented by the papers on various 

 phases of the subject that have appeared from time to time since their publica- 

 tion, may be of general interest. 



Ants, Bees and Wasps. 



The great order,- including the ants, bees, wasps, small four-winged jnira- 

 sites, and gall-forming and plant-eating wasp-like insects, is well represented 

 in Hawaii. The order is divided into two sub-orders, one the boring,^ the 

 other the ^iingm'g^ Hymc no pt era. In the former sub-order, among other 

 characteristics, the tip of the abdomen in the females is provided witli an 

 organ suited to boring the hole into which the Q2.g, is deposited. In some 

 species this instrument is used to drill holes in trees, in others it is used to 

 thrust the egg into the body of some other insect where it develops. Many of 

 the species are very minute : often their existence is accidentally discovered 

 during the process of rearing other insects in breeding jars. At such times the 

 tiny parasite often emerges from the body of its host and appears in the jars as 

 a microscopic insect with four wings. These are known as |)arasitic Hijhk imp- 

 tem, and are of great biologic importance in keeping tluMr host species in 



- Hymenojitem. ^ Terehraittiit. * Acideata. 



