Bugs, Cicadas, Aphids, and Scale-insects 183 



in the form of very minute white fibrous waxy filaments, which spring from 

 all parts of the body and rapidly become more numerous and dense. At 

 first the orange color of the larva shows through the thickening downy white 

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

 white or pale grayish-yellow shell or scale, which now has a prominent central 

 nipple, 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 hemi- 

 sphere. The matting of the secretion 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 

 grayish-yellow color, turning gradually darker gray, the central nipple 

 remaining lighter colored, usually throughout development. 



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

 until after the first moult, which occurs twelve days after the emergence of 

 the larva. With this moult, however, the insects beneath the scale lose all 

 resemblance to each other. The males (Fig. 252, a) are rather larger than 

 the females, and have large purple eyes, while the females have lost their 

 eyes entirely. 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 condition 

 (propupa), and the male scales assume an elongate oval, sometimes slightly 

 curved shape, characteristic of the sex, the exuvia or cast larval skin show- 

 ing near the anterior end. The male propupae are very pale yellow, with 

 the legs and antennas (which have reappeared) together with the two or three 

 terminal segments colorless. . . . Prominent wing-pads extend along the side 

 of the body. 



"The female undergoes a second moult about twenty days from the 

 larva. At each moult the old skin splits around the edge of the body, the 

 upper half adhering to the covering scale and the lower forming a sort of 

 ventral scale next to the bark. This form of moulting is common to scales 

 of this kind. 



"The covering scales at this stage are of a more purplish gray, the por- 

 tion covering the exuviae inclining to yellowish. The male scales are more 

 yellowish than the female. The effect of the sucking of the insects is now 

 quite apparent on the young growth, causing the bark to assume a pur- 

 plish hue for some distance around the central portion, contrasting strongly 



