TRIBE DIASPIDINI 299 



of scale is circular or subcircular. The exuviae overlap in the 

 circular scales just as in the pyriform scales or mussel-shaped 

 scales, but they are frequently placed so that they do not project 

 beyond the periphery of the scale. There may be in fact a nar- 

 row area of wax between the cephalic end of the first exuvia and 

 the periphery or the exuviae may project very slightly beyond the 

 periphery, only the first exuvia protruding, or the exuviae may 

 protrude for a considerable distance, for as great a distance as 

 in the pyriform scales. In the location of the exuviae, even in 

 different individuals of the same species, there may be consider- 

 able variation, sometimes being placed parallel or nearly so with 

 the margin and at others perpendicular to it. When the exuviae 

 project a considerable distance beyond the periphery of the scale, 

 the wax of the scale adjacent to the exuviae is sometimes extend- 

 ed so that the scale becomes slightly prolonged and approaches 

 the pyriform type. The scales, while they are more often white 

 than any other color, are often grayish or blackish, particularly 

 in the genus Chionaspis. The texture of the scale in many species 

 as in those of the genus Diaspis and its allies is very thin, semi- 

 transparent, tough, and parchment-like. In the darker colored 

 mussel-shaped scales, they are more coriaceous and leathery like 

 the scales of the genus Lepidosaphes. The exuviae overlap each 

 other and the first nymph bears the remains of the antennae 

 as porrect projections. The exuvia of the second nymph is 

 about three or four times as long as that of the first. It is 

 always much less in extent than that of the wax of the scale, 

 covering one-fourth or less of the area of the scale. Only a very , 

 few of the species transform in a puparium which explains why 

 the second exuvia is generally not very large. The ventral scale is 

 extremely variable in extent and texture, it may be very thin and 

 delicate and remain attached to the host-plant when the dorsal 

 scale is lifted or it may be stout and thick and retain its con- 

 nection with the dorsal scale when removed. 



The scales of certain species of Chionaspis resemble closely 

 the scales of most of the species of Lepidosaphes, some individ- 

 uals resembling them so closely that it is necessary to examine 

 the body of the female to be sure of their correct generic position. 

 The Latin word aspis from which so many of the generic names 

 in this subfamily are compounded means a shield. This may 

 have been applied originally to the scale as a whole, but evident- 

 ly in the case of the generic name Diaspis from which the ^ name 

 of this subfamily and tribe is derived, refers to the exuviae of 



