212 



APPLIED ENTOMOLOGY 



its edge to near the center where a slight circular depression surrounds 

 the raised center or " nipple" itself. It is brownish-gray in color when 

 adult, but in earlier stages may vary from this. The adult male scale 

 is somewhat smaller, more oval in outline, and with the nipple not cen- 

 trally placed but nearer one end. 



At the beginning of the winter season specimens of this scale of 

 practically all ages occur, but probably only those from about one-third 

 to one-half or two-thirds grown survive the winter. In the spring these 



individuals resume their feeding on 

 the sap and after a time the males 

 appear. In the northern states 

 this condition is hardly reached 

 before the middle of May, but at 

 Washington, D. C. it comes early 

 in April, and farther south still 

 earlier. After mating, the females 

 continue to grow and about a 

 month later the first young appear. 

 These do not, in the San Jose 

 Scale, hatch from eggs laid by the 

 parent but the young are born 

 alive; i.e., this insect is viviparous. 

 These young are produced, a few 

 every day or two, and the parent 

 lives for a month or more, pro- 

 ducing an average total of about 

 FIG. 205. San Jose Scale (Aspidiotus 400 young. These resemble the 

 pernidosus Comst.) : adult female scales crawling young of the scales already 



enlarged about five times. (From Houser, i i 



Ohio Agr. Exp. Sta. Bull. 332.) considered, except that they are 



lemon yellow in color, and they 



crawl about and settle down to feed in the same way. The scale 

 now begins to appear, at first as white waxy threads over the back, 

 which soon mat together to form a pure white covering. As the 

 nymph beneath molts, the molted skins are added to this and variations 

 in color of the scale appear. Sometimes the scale of the partly grown 

 insect may show white, black and gray, varying in arrangement according 

 to the completeness with which the different parts have combined, but 

 before maturity it becomes a quite uniform grayish-brown. The young 

 become adult in a little over a month and then themselves begin to 

 produce young, and in the northern states there are usually at least 

 three generations in a season, while in the south there are four or even 

 more. The generations overlap, the earliest young produced by the 

 second generation for example, sometimes appearing before the last born 

 of the preceding one, which results in the almost constant presence of 



