SCALE INSECTS OF IMPORTANCE 349 



On the dorsal side the anus is easily detected. The dorsal pores are 

 small and clean-cut and usually run in two rows, on either side of the 

 median line, one from the second incision toward the lateral transverse 

 chitinous thickening and the second row laterad of that and running 

 clear to the outer end iof the same thickening, one pore usually being 

 against the thickening. The number of these pores is variable but I have 

 several times counted six or eight in each row. At the first incision 

 there are two or three pores. 



The second stage of A. forbesi (pi. 13, fig. i) resembles the third in 

 general, though, of course, it is smaller in size. At this stage, the second 

 lobes seem somewhat smaller comparatively and are more often rounded 

 than notched. The characteristic approximation at the tips usually occurs, 

 and aids in distinguishing this form from the second stage of A. p e r- 

 n i c i o s u s which usually shows nearly parallel lobes. The chitinous 

 processes are usually of the characteristic shape, but sometimes are not 

 so marked in disparity of size as in the adult. The spines and plates are 

 as in the adult. The ventral glands are of course wanting, and the ventral 

 thickenings are faint and indefinite, as in the others of these four species. 

 The dorsal pores are fewer than in the adult but represent in scattering 

 lines the arrangement of the later stage. Quite often one may be 

 observed even beyond the lateral chitinous thickenings. 



Aspidiotus perniciosus Comst. 



PLATES 12 AND 1 3, FIGURES 2 



The adult female of the pernicious or San Jose scale shows two distinct 

 pairs of lobes, which, while approximating somewhat at the tip, do not 

 usually come so close together as in A. forbesi. The median lobes are 

 rather long and narrow in appearance, are deeply notched on the outer 

 margin and often on the inner margin nearer the tip than is the outer 

 notch. The second lobes are distinct, well marked, about half the size 

 of the first, rounded at the tips and notched on the outer margin. The 

 spines are as in aUied species, one on each lobe, one beyond the second 

 incision and the fourth about halfway from the lobes to the penulti- 

 mate segment. The plates are quite numerous and easily distinguishable, 

 giving a somewhat fringed appearance that helps to differentiate this 

 species from A. forbesi. There are usually two inconspicuous plates 

 between the median lobes, and two or three long and slender ones at the 

 first incision, three or two often somewhat serrate ones at the second 

 incision and three broad, often two-pointed ones, between the third and 



