1 82 Bugs, Cicadas, Aphids, and Scale-insects 



out. The structural t haratteristics and life-history of the insect may lie 

 briefly described as follows: 



There may be seen on infested branches, leaves, or fruit, small, flat, 

 grayish, irregularly circular scales of varying size (Figs. 250 and 251), the 

 large stones (about j^ '"^h diameter) being the adult females and the smaller 



ones being the immature individuals 

 of both sexes. These circles arc thin 

 wa.xen plates, bearing one or more (de- 

 pending on the age of the individual) 

 faintly yellowish concentric inner cir- 

 cles or plates (the inner one usually 

 blackish and like a tiny nipple) which 

 are the moulted exuvia; of the scale. 

 When the plant is badly infested the 

 scales lie thickly together, even overlap- 

 ping, and forming a sort of grayish 

 scurf over the smooth bark. By rubbing 

 or crushing this scurf a yellowish oily 

 licjuid issues from the injured bodies. 

 If a scale be tipped over with a pin- 

 point, there will be found underneath 

 it a delicate flattened yellowish sac-like 

 creature, the insect itself (Fig. 252). 

 If adult, this degenerate female will be 

 seen (by examination with magnifier) 

 to have no distinct head, no eyes nor 

 antenna;, no wings nor legs. It does have a long, fine, flexible, thread-like 

 process projecting from near the center of its under side; this is the suck- 

 ing proboscis, and serves as a means of attachment to the plant as well 

 as the organ of feeding. 



Early in the spring, females which have hibernated under their pro- 

 tecting armor begin giving birth to living young, and continue doing this 

 actively for about six weeks, when they die exhausted. The minute orange- 

 yellow young, which have eyes, antenn;c, and three pairs of legs, crawl out 

 from under the scale and run about actively for a few hours over the twigs 

 or leaves; then they settle down and each* "slowly works its long bristle- 

 like .sucking-beak through the bark, folds its antenna^ and legs beneath its 

 body and contracts to a nearly circular form. The development of the 

 scale begins even before the larva becomes fixed. The secretion starts 



Fig. 251. — The San Jose scale, Aspi- 

 dioius perniciosiis, females and young, 

 on bark of fruit-tree. (From living 

 specimens; at left, natural size; at 

 right, considerably enlarged.) 



* The foUomng long quotation is made from Howard and Marlalt's " The San Jos^ 

 Scale " (Bull. 3, N. S., Div. Ent., U. S. Dcpt. Agric, 1896). 



