HEMIPTERA, 149 



adult the supplementary eyes which takes the place of the mouth- parts is 



not shown. 



The genera of the Diaspinae are characterized chiefly by the form 

 of the scales, and the position of the moulted skins or exuviae upon 

 them. In the use of these characters it is necessary to distinguish 

 the sex of the individual by which a given scale was made. This 

 can be done as follows: In the scale of the fully developed female 

 there are two moulted skins, while in that of the male there is but 

 one. Our genera can be separated by the following table :* 



A. Scale of female circular with the exuviae either central or more or less 

 nearly marginal. 



B. Scale of male but little elongated, with the exuviae more or less central ; 

 scale usually resembling that of the female in color and texture (Plate 

 VII. Fig. la and 20). ASPIDIOTUS. 



BB. Scale of male elongated, with the exuviae at one extremity. 

 C. Scale of male, white and carinated (Plate VII. Fig. 3*7). DIASPIS. 



CC. Scale of male, not white and with no central carina (Plate VII. 

 Fig. &?). PARLATORIA. 



AA. Scale of female elongated, with the exuviae at one extremity. 

 D. Exuviae small. 



E. Scale of male, white and carinated t (Plate VII. Fig. 4*); last 



segment of female with five groups of spinnerets. CHIONASPIS. 



EE. Scale of male white, but not carinated; female with eight groups 



of spinnerets. POLIASPIS. 



EEE. Scale of male similar in form to that of the female (Plate VII. 



Fig. s). MYTILASPIS. 



DD. Exuviae large. 



F. Two moulted skins visible on the scale of the female (Plate VII. 



Fig. 7, 8). PARLATORIA. 



FF. "second skin covered by a secretion (Plate I. Fig. 9). UHLERIA. 



The accompanying illustrations, from my report on scale-insects 

 in the Report of the U. S. Dept. of Agriculture for 1880, will enable 

 the reader to recognize the more important species of this sub-family. 



Aspidiotus.* is the largest genus of the Diaspinae ; more than 

 twenty species have been observed in the United States. The one 

 which has done the greatest injury to citrus fruits on the 

 coast is the Red Scale of California, Aspidwtus aurdntii (Plate VI. i). 

 Closely allied to this is the Red Scale of Florida, A.ficus (. 



* From the author's Second Report on Scale-Insects ; published in the Second Report 

 of the Cornell University Experiment Station. Ithaca, N. Y., 1883. 



f In Chionaspis ortholobis the scale of the male is not carmated. 

 willow in California. 



