THE ANIMAL LIFE OF THE GROUP. 427 



Plant-Lice. 



The sub-order'-'^ to which the plant-lice, the jumping- plant-lice, the lan- 

 tern-flies and similar insects belong, is made to include a number of odd bugs 

 with suctorial mouth parts. Though they dift'er widely in form, they usually 

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

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

 sides of the body. 



Leap-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 Avhich, like the lantern-fly 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 i^"' 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 difSciflt to identify spe- 

 cifically. 



In a synopsis of the family of Aphids or plant-liee.i^i 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 Alcyrodiclce, which formei-ly were included with the scale-bugs and 

 mealy-bugs,!'*- are represented by six known species, while the coccids have 

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

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

 two are thought by specialists to belont;- to the native insect fauna. 



TlIRIPS. 



The thrips'-'"'^ are microscopic insects so small that they rarely attract the 

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

 adults show their four long narrow wings, of nearly equal size, to be fringed 

 with long hairs. These are laid horizontally on the back when at rest. How- 

 ever, in many of the Hawaiian species the wings have been reduced to func- 

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

 and moss, and on the undeiside of stems, leaves and stalks of grass, plants and 

 shrubs. Their mouth parts show them to be intermediate between the suck- 

 ing and biting insects, and, as one woiild expect, they are known to feed on 

 other insects and upon vegetation. Four famili(\s are represented l)y twenty 

 or more species, the most of which are l)lacl';. Iirown or cliestnut-lirown in color. 



^** Homoptera. ^*^ Membracidtp. ^*" Ceitti-'Ai/ixis sp. ^*' Trttis/fiuiidtr. ^*^ FulgoridcE. 

 i*» Perkinniella aaceharicida. i^" Asiracida'. ^^^ Aphidce. ^^- Coccidcr. i^s Thysanoptera. 



