INTRODUCTORY REMARKS. 



Since the cane leaf-hopper has become so abundant in the 

 Hawaiian Islands, certain predaceous insects have taken to 

 feeding upon them and have likewise increased in abundance; 

 so that they are now found as constant inhabitants of the cane- 

 fields wherever leaf-hoppers are abundant, and are of no little 

 value in helping to check the increase of the latter. 



Of the insects treated in this Part the grasshopper {Xip- 

 hidiiim) is by far of the most importance. It is not indigenous 

 to the Islands, but from whence it came is not known. Its in- 

 troduction was accidental about 15 years ago. There are many 

 species of this genus in all parts of the world. I have seen no 

 mention of any species being insectivorous, they being chiefly 

 grass feeders. It is not unlikely that our species has developed 

 its partial insectivorous habit since its introduction here, and 

 shice the increase of the leaf-hoppers to such an abundant food- 

 supply. 



The bugs (Hemiptera) treated of, with the exception of Zclus 

 percgrinus, are native to the islands, and have l^ecome adapted 

 to a leaf-hopper diet by reason of the fact that this pest fur- 

 nishes a convenient and bountiful food supply. They are not 

 feeding exclusively upon this new source of food, but may be 

 found as well in their former habitats feeding upon their orig- 

 inal prey. 



The ladybugs treated of are primarily Aphis feeders, and have 

 all been introduced from Australia. When found in cane-fields 

 there is no doubt but that they have been especially attracted 

 by the cane Aphis, which is usually more or less present in 

 fields of young cane. Coccinella rcpanda, the ladybug which has 

 been the longest introduced, is very common in all parts of all 

 the islands; when in cane fields, it also preys upon young leaf- 

 hoppers, especially when its food-supply of Aphis is scarce or 

 has become ex'hausted. It is very probable that the recently 

 introduced species will do the same when they have become 

 established and generally distributed, and that they will be a 

 valuable addition to the present force of predaceous insects 

 preying upon the leaf-hopper pest. 



Heretofore the life history of none of the insects herein treat- 

 ed has been studied. In the observations recorded in this paper, 

 a number of new and interesthig facts pertaining to life history 

 have been brought out. 



