28 



PART II. 



By F. MuiR. 



DERBIDAE. 



INTRODUCTION. 



IIAIJITS. 



The species described in this Ikilletin (except a few specially 

 indicated) were collected during the time I was in Fiji and the 

 Malay Archipelago, investigating insects injurious to sugar-cane. 



Many species of this family are to be found in great numbers 

 on sugar-cane, but only in the adult stage ; the young and eggs I 

 have never found on this host-plant. I am not acquainted with 

 any record of the life-history of any species of this family, and 

 I have never come across the eggs, but I have taken the nymphs 

 of several species, all having similar facies and hal^itat. All these 

 nymphs were living in rotten tree trunks, were dark in color, 

 flattened horizontally, with wide faces, even in such forms as 

 Zoraida: both in appearance and habitat tliey are similar to 

 many species of O Hants, but the females do not possess the large 

 wax-plate at the end of the abdomen. Although the adults of 

 some species collect in such numljcrs in cane fields, where they 

 are very conspicuous on account of the habit they have of often 

 sitting near together, in Indian-file, with their long wings over 

 their backs, yet they never do any considerable damage ; this must 

 be attributed to the habit of the young of not feeding on sugar 

 cane, for if they did their number, which is much greater than 

 that of the adults, would cause considerable damage. 



Another strange feature of these swarms of Derbiclae is that 

 they generally consist of only one sex and at such times it is very 

 difficult to find the opposite sex. 



That this interesting family of leaf-hoppers has been greatlv 

 neglected is shown by the fact that we know so little about their 

 life histories and that I. although only collecting them inciden- 

 tally, have been able to add 16 genera and 96 specie;^ to it. My 

 collection is by no means representative as, confined to the culti- 

 vated areas by my special work, I collected but little in the natural 

 forest where these forms are most numerous and diversified. 



None of this family exists in the Hawaiian Islatids, and even 

 if one or more species should ever become established here, the 

 fact of the young living in rotten timber would confine them to 

 verv limited areas. 



