240 THE COCCIDAE 



the first exuvia remains in a single piece and since the antennae 

 remain attached to the dorsal portion of the exuvia, it is possible, 

 unless they have been broken off by the elements, to identify the 

 antennae on the first exuvia of the adult scale. The presence 

 or absence of the antennae on the dorsal portion of the first exuvia 

 may prove of value in determining the tribal location of a given 

 species. 



The scales vary greatly in shape. In some species the 

 exuviae are nearly as large as the entire scale, while in others 

 they are not only much smaller but form only a small portion of 

 the scale in comparison with the much greater extent of the wax 

 or excreted portion. Where the scales are elongate, the exuviae 

 are placed at one end and usually project beyond its margin. The 

 portion of the scale bearing the exuviae is always narrow and 

 the scale gradually widens toward the caudal end. In the circu- 

 lar scales the exuviae are usually placed within the periphery and 

 in the Aspidiotini, which usually have this type of scale, they 

 are located at or near the center of the scale. The body of the 

 insect is generally located under or near the exuviae. 



The young nymphs of the first stage usually form a minute 

 ball or button of threads of wax as the first part of their scale. 

 This becomes melted into a compact mass and can be identified 

 as the minute dot over the first exuvia of the scales of many 

 adult females. This dot may be known as the cicatrix. Corn- 

 stock has described and figured the peculiar rolls of cicatrices 

 formed by certain individuals which do not get beyond this stage 

 in the formation of their scale. 



The scales of all adult females contain typically two exuviae. 

 A few genera in most of the tribes as Aonidia do not molt their 

 second exuvia, but shrink away from it and transform to adults 

 within it, using this second exuvia as a puparium which conse- 

 quently never becomes attached to the scale. Some of the species 

 transforming in a puparium, particularly those with a long or 

 pyriform scale, have a transparent scale so that the puparium 

 can be identified through the scale and from its position appears 

 to be the second exuvia. With the exception of these genera, the 

 presence of a single exuvia indicates that the enclosed insect is 

 in the second nymphal stage if a female or if a male, that it is in 

 any stage after the first nymphal stage. The scales of the males 

 are always much smaller tlian those of the adult female, are 

 usually quite similar to those of the second nymphal female, and 

 are always provided with a single exuvia. In a few genera as 



