s 



CIRCULAR 3 6 5, U. S. DEPARTMENT OF AGRICULTURE 



settles, or inserts its 

 beak and begins feed- 

 ing. After settling, 

 the nymph secretes 

 over its body a waxy 

 substance in the form 

 of delicate white 

 threads, which coa- 

 lesce into a solid white 

 covering (fig. 3). In 

 a few days this cover- 

 ing takes on a yellow- 

 ish color, which dark- 

 ens as the scale ages, 

 until, in the case of 

 the reproducing fe- 

 male, it assumes a 

 characteristic choco- 

 late-brown hue, al- 

 though in the latter 

 part of the summer it 

 is sometimes slate 

 gray. \Vhen not 

 crowded by other 

 scales, the covering of 

 the female is nearly 

 circular and distinctly 

 arched, with a subcen- 

 tral apex or nipple 

 (fig. 4) . At its maxi- 

 mum size it is one- 

 eighth to one-sixth 

 inch in diameter. 

 There is also a fragile 

 layer of white wax 

 underneath the fe- 

 male, and this usually 

 adheres to the bark 

 of the plant when the 

 insect is removed, 

 forming the so-called 

 white " scars." 



After settling, the 

 nymph becomes 

 rounded and gradu- 

 ally loses its purple 

 hue, becoming white 

 to flesh-colored. In 

 the course of her 

 growth the female molts twice, fertilization taking place after the sec- 

 ond molt. Preceding each molt, her body becomes swollen and its con- 

 tents fluid, and for a few days the dorsal integument adheres to the cov- 

 ering, with which it is incorporated when the skin is shed. As the adult 

 female ages, she becomes pink, then purple, often with developing eggs 



Figure 3. — Newly settled scales on a camphor-tree twig. 

 The covering has been raised from the reproducing 

 female, giving a dorsal view of the scale. Enlarged 9 

 times. 



