SUBORDER HOMOPTERA 



A curious and important assemblage of insects belong to the 

 Homoptera. Those creatures which we know as leaf-hoppers, 

 tree-hoppers, cicadas, plant-lice, flea-lice, bark-lice, scale insects, 

 mealy bugs, and white flies all belong here. Their name is 

 legion and they are without exception, destructive to plant life. 

 Their mouth-parts are formed for sucking, and their transforma- 

 tions are incomplete. Their forewings are not modified, as with 

 the Heteroptera, or true bugs, but are more normal and are 

 usually held roof-like over the back when at rest. The front of 

 the head is always bent under so that it touches the base of the 

 front legs. Beyond these points, their structure is very diverse, 

 and beyond the fact that all are plant feeders their habits are also 

 very diverse. In their life histories some of them, particularly 

 the plant-lice, the bark-lice and the periodical cicada (or so- 

 called seventeen-year locust), present some of the most interest- 

 ing, and, in fact, some of the most astonishing, phenomena in 

 the whole field of biology. The progressive degradation, after 

 birth, of the female of the scale insects, from an active, highly 

 animated creature to a blind, legless, protoplasmic globule, and 

 the contrasting development of the male of the same species, 

 from a minute, crawling mite to a virile, winged, active and 

 highly organized creature whose head is practically all eyes, is 

 one of the most extraordinary life histories among all insects, 

 while the alternate forward and backward development which 

 occurs in the genus Margarodes in this family is even more 

 strange. Then, too, the remarkably adapted parthenogenetic life 

 of the plant-lice, with their alternation of food plants and their 

 relations with ants, make their study one of fascinating interest. 



The Homoptera is a large group of insects. No one knows 

 how large. The plant-lice and the scale insects of Europe and 

 North America have been rather well studied, largely on account 

 of the economic interest which attaches to them. Yet, even from 

 North America, many new species are being found, even in these 



228 



