THE ANIMAL LIFE OF THE GROUP. 427 



Plant-Lice. 



The sub-order i-*^ to wliicli tlie plant-liee, the jumping' plaut-licc ilic hiii- 

 tern-tlies and similar insects belong, is made to include a number of odd Ijugs 

 with suctorial mouth parts. Though they differ widely in form, they usually 

 agree in that when the wings are present they are of the same thickness 

 throughout. When at rest their Avings are held slanting, roof-like, at the 

 sides of the body. 



Leaf-Hoppers. 



The tree-hoppers I'*" if represented in the fauna are included only as 

 recent introductions; one species^*" was taken as long ago as 1908. The leaf- 

 hoppers,'^' better known as jassids, are slender, minute, inconspicuously-colored 

 insects which, like the lantern-tly family i^"* and closely-allied families, are 

 represented in the Hawaiian fauna by a very few species. The sugar-cane 

 leaf -hopper 1^'' is by far the most destructive member of a family'^*' to which 

 have been referred ten genera, including thirty species of Hawaiian insects. 

 They are arboreal in habit, favoring the higher elevations. They average 

 about four millimeters in length and are extremely difficult to identify spe- 

 cifically. 



In a synopsis of the family of Aphids or plant-lice,' -^^ Prof. D. T. Fullaway 

 enumerates twenty-one species belonging to eight genera as occurring in the 

 Hawaiian fauna. A large number of these are of economic importance, and 

 have had notice in a chapter devoted to that phase of the local insect life. 



The Alcjjrodidie, which formerly were included with the scale-bugs and 

 mealy-bugs/'^- are represented by six known species, whih' the coccids have 

 close to one hundred species in the fauna, almost all of Avhicli have been 

 brought to Hawaii within the last one hundred years. Of this number only 

 tAvo are thought by specialists to belong to the native insect fauna. 



Thrips. 



The thrips '•"'•^ are microscopic insects so small that they i-iitIv jitlract tbe 

 attention of even observant persons. Under a hand lens oi- the microscope the 

 adults show their four long narrow wings, of nearly ecpial si/c. to be fringed 

 with long hairs. These are laid horizontally on the Itack when at n^st. How- 

 ever, in many of the Hawaiian species the wings liave been i-educed to func- 

 tionless pads. Thrips are to be found in various places, as in flowers, lichens 

 and moss, and on the underside of stems, leaves and stalks of grass. |)liints and 

 shrubs. Their mouth parts show tlieiii to he iiilcriiii'<li;ite between tlie suck- 

 ing and l)iting insects, and, as one would ('Xjx'cl. llicy are known to \'viH\ on 

 other insects and upon vegetation. Four families arc I'cpresented by twenty 

 or more species, the most of which arc black, bi'own oi- ciu'stnnt-brown in color. 



^^* Ilomopft'i-a. ^^^ Mi'}iihracida'. ^"^ Cetitroli/iiiis sp. ^*' Teltigoniidce. ^*^ Ftd<iorid(c. 

 1*" Perkinsu'lla media ririda. ^^o Asiracidiv. i^^ Aphida;. i"- Coccidce. i^' Ilninnnoptera. 



