CHAPTER XXVI 



SOME INSECTS INJURIOUS TO ORCHARD FRUITS 

 The San Jose" Scale * 



PROBABLY the most serious of all the insect pests of the orchard 

 is the San Jose Scale, for it will kill young trees in two or three 

 years, and old trees must be sprayed annually to keep it under 

 control. So insidious is the attack of the pest to those unfamiliar 

 with it that it has killed many thousands of trees before 

 the owners suspected its presence. It may be most readily 

 detected on the fruit, which becomes spotted with small red 

 circles which form around the scales, but usually the fruit is 

 not attacked until the tree is badly infested. On the young 

 twigs and along the veins of the leaves a similar reddish discolor- 

 ation appears around the scales. The trunk and branches covered 

 with scales have a rough grayish appearance, as if they had been 

 coated with, dark ashes. By scraping the surface the soft, juicy, 

 yellowish insects will be revealed beneath the covering scales. 

 If a single female insect be examined it will be found that it is 

 covered by a small, circular scale, varying from grayish to blackish 

 in color, formed of concentric circles, the centre of which is quite 

 convex and forms a " nipple," which is yellowish and shining 

 when the surface is rubbed off. If this scale be raised with a 

 pin, beneath it may be seen a small, soft, oval, orange-colored, 

 object, which is the true female insect. She is an almost shape- 

 less mass of protoplasm, lacking head, legs, and eyes, only 

 the thread-like mouth parts and anal plate being distinct. The 



* Aspidiotus perniciosus Comstock. Family CoccidoB. See C. L. Mar 

 latt, Bulletin 62, Bureau of Entomology, U. S. Dept. Agr., and the numer- 

 ous publications of many of the experiment stations, listed in his 

 bibliography. 



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