LIFE HISTORY. 45 



different generations. The course of the development t)f a single 

 generation follows: 



After being expelled the larva remains motionless for a little while, 

 with antennae and legs folded beneath the body. It soon hardens 

 enough to run about, and, forcing its way out from beneath the pro- 

 tecting scale of the mother, scurries over the plant to find a suitable 

 place to settle. 



The newly born larva {&g. 3, a) is an almost microscopic creature of 

 pale orange-yellow color, with long oval body, and with the customary 

 six legs and two feelers. The long thread-like proboscis with which 

 the juices of the plant are sucked up is doubled on itself and lies in an 

 invagination of the body wall, the tip only projecting. 



After crawling about for a few hours the young larva settles down 

 and slowly works its long bristle-like sucking beak thru the bark, 

 folds its antennae and legs beneath its body, and contracts to a nearly 

 circular form. The development of the scale begins even before the 

 larva becomes fixt. The secretion starts in the form of very minute 

 white fibrous wax}^ filaments, which spring from all parts of the body 

 and rapidly become more numerous and dense (fig. 3, J, c). At first the 

 orange color of the larva shows thru the thickening downy white 

 envelop, but within two days the insect becomes entirely concealed by 

 the white or pale grayish yellow shell or scale, which now has a promi- 

 nent central nipple (fig. 3, d)^ the younger ones often possessing instead 

 a central tuft. The scale is formed by the slow matting and melting 

 together of the filaments of wax. During the first day the scale appears 

 like a very microscopic downy hemisphere. The matting of the secre- 

 tion continues until the appearance of down and individual filaments is 

 entirely lost and the surface becomes smooth. In the early history of 

 the scale it maintains its pale whitish or gra3nsh yellow color, turning 

 gradually darker gray, the central nipple remaining lighter colored 

 usually thruout development. 



The male and female scales are exactly similar in size, color, and shape 

 until after the first molt, which occurs twelve days after the emergence 

 of the larva. With this molt, however, the insects beneath the scale 

 lose all resemblance to each other. The males (fig. 4, a) are rather larger 

 than the females and have large purple e}' es, while the females have lost 

 their eyes entirel3^ The legs and antennae have disappeared in both 

 sexes. The males are elongate and pyriform, while the females are 

 almost circular, amounting practically to a flattened sac with indistinct 

 segmentation, and without organs, except a long sucking bristle 

 springing from near the center beneath. The color of both sexes is light 

 lemon-yellow. The scales at this time have a decidedly grayish tint, 

 overcast somewhat with yellow. 



Eighteen days from birth the males change to the first pupal condi- 

 tion (pro-pupa) (fig. 4, 5), and the male scales assume an elongate oval, 



