178 



INJURIOUS AND BENEFICIAL INSECTS OP CALIFORNIA. 



Nature of Work. — All for 

 and small twigs of the host 

 into the bark and may be 

 completely hidden from 

 view. Large limbs or en- 

 tire trees may be killed by 

 their attacks, which greatly 

 resemble those of the San 

 Jose scale. 



Distribution. -This scale 

 appears to be quite widely 

 distributed throughout the 

 southern part of the State. 

 It has become quite a pest 

 to walnut trees in Orange 

 County. 



Food Plants. — Apple, 

 apricot, white ash, prickly 

 ash, box-elder, cherry, Cot- 

 tonwood, currant, elm, lin- 

 den, locust, maple, peach, 

 pear, plum (domestic) , 

 plum (wild), prune, rose, 

 sweet gum and English 

 walnut are hosts of the 

 walnut scale. 100 



Control.— The remedies 

 are the same as for San 

 Jose scale. 



Natural Enemies. — The 

 following internal hymen- 

 opterous parasites have 

 been reared from the Eng- 

 lish walnut scale: the 

 golden chalcid (Aphelinus 

 diaspidis How.), Encyrtus 

 ensifer, Prospaltella au- 

 rantii How. and Signiphora occidentalis How. 



ms settle upon the trunks, large branches 

 plants. The adults often appear to mine 



Fig. 156. — The walnut scale, Aspidiotus jug- 

 lans-regioe Comst., on English walnut. Elnlarged 

 twice. Collected at Anaheim by Roy K. Bishop. 

 (Original) 



THE EUROPEAN FRUIT-TREE SCALE 

 Aspidiotus ostnii formis Curtis 



Description. — The scales of the full-grown females are nearly cir- 

 cular, dark ashy-gray with the exuviae dark orange-colored and sub- 

 central. The diameter is about xV inch. The male scales differ only 

 in being somewhat smaller and more elongated. 



Life History.— The life history of this scale is not materially dif- 

 ferent from that of the San Jose scale. 



""Yearbook, U. S. Dept. Agric, pp. 300-301, 1880. 



