New YorK AGRICULTURAL EXPERIMENT STATION. 305 
the molted skins showing through the scale. In many cases the 
nipple is near the margin as shown at Plate XLIX, Fig. 1: The 
two large scales in this picture are adult females. The first molt 
causes the whole central area of the scale to appear a lighter 
shade than the remainder. The white cottony mass which is 
forced beyond the edges of the scale turns dark, forming a dark 
ring. The second molt forms a lighter area, which, as it shows 
only toward the edge, the scale now being much thinner at the 
edges than toward the apex, forms a lighter ring. Thus there 
are two more or less distinct broad light bands with a narrow 
dark band between. Plate XLVIII, Fig. 7. At Plate XLVITI, 
Fig. 8, a mature scale is shown turned back exposing the living 
insect. The dark area forming the posterior extremity of the 
insect’s body is the anal plate. It is by means of the microscopic 
characters of this plate that the species may be definitely deter- 
mined. Plate L, Fig. 1 is from a photomicrograph of the anal 
plate of the San José scale, and Fig. 2 of Aspidiotus wstreeformis, 
a species common in this State that is sometimes mistaken for it. 
While the above description of scale formation is fairly typical, 
there is much variation. In this connection the following notes 
giving the details of the formation of the scales of a number of 
individuals kept under the same conditions may be of interest. 
All of the larve were placed on smooth-skinned apples and kept 
in the laboratory or insectary. 
No. 1.—Ten larve born September 4. By September 8 they 
were completely covered by the white cottony secretion. On this 
date the cottony mass was removed, but by September 10 it was 
replaced by another covering of waxy filaments which were more 
closely matted together than the former. The scales were white 
like the first and on this date showed a faint indication of a cen- 
tral nipple but noring about the nipple. By the following day a 
slight ring-like depression had formed about the nipple. Until 
September 19 there was no apparent change but on that date 
the scales appeared to be turning darker in color. By September 
21 they had begun to turn very dark, nearly black on the outer 
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