138 HEMIPTERA. 



Phylloxera, an interesting genus, has been studied, 

 and the hfe-history of several species admirably worked 

 out by Dr. C. V. Riley.^ These are pests of the grape- 

 vine, and for those living in favorable localities this 

 form might be advantageously studied. 



The tree-hoppers are very curious little insects, 

 frequently brought in by children. The body is com- 

 pressed and thin, having sometimes a triangular appear- 

 ance, due to the very broad prothorax, which extends 

 backward in an extraordinary way, often covering a 

 large part of the body, and sometimes forming horns 

 or humps. 



C(3CCID.^i. 



The female of the scale insect is an instructive 

 example of speciaHzation by reduction, while the male 

 imitates the flies in some characters. The process of 

 reduction is carried so far in the female of some spe- 

 cies that all trace of segmentation is lost. Fig. Zt^, a, 

 is the scale or female of Lecanium found on the 

 maple ; Fig. '^t^, b, the same species, occurs on the 

 Osage-Orange. In the Report of the Entomologist 

 for 1884 (see also American Naturalist, June, 1885, 

 pi. xviii.), Riley has figured the ^g%, larva, female 

 scales, and adult male and female of this species, 

 under the name of Piilvinaria innumerabilis. This 

 entomologist has also observed the development of 

 Aspidiotus conchiformis ? 



1 Sixth and Seventh Reports A^oxioiis and Beneficial Insects 

 of Misso tiri, 1874-75. 



'^ For figures, see Packard's Guide to the Study of Insects, p. 

 529. 



