184 



INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



fornia fan palm, date palm, passion vine, pear, pistacia, Podocarpus, 

 privet, quince, rose, sago palm, tangerine, tea, English walnut and 

 willow are attacked. 



Control.— Fumigation with full schedule No. 1 is specially recom- 

 mended. Spraying is only efficacious on deciduous fruit trees with 

 lime-sulphur (1 to 9), miscible oil sprays, crude oil or distillate 

 emulsion. 



Natural Enemies. — The ladybird beetles, Orcus chalybeus Boisd.. 

 Lindorus lopanthus Blaiscl., Chilocorus bivulnerus Mul., Scymnus mar- 

 ginicollis Mann., Scymnus nebulosus Lee, Hippodamia convergens 

 Guer., Hippodamia ambigua Lee, Coccinella californica Mann., the 

 green lacewing (Chrysopa californica Coq.), the brown lacewing 

 (Sympherobius angustus Bks.) ; some 

 of the members of the hemipterous 

 family Eeduviidce ; the internal para- 

 sites, Prospaltella aurantii How.. 

 Coccophagus lunulatus How., Aspidi- 

 otiphagus dtrinus Craw., Signiphora 

 occidcntalis How., Aphycus immacu- 

 latus How., Alaptus criococci Girault 

 and Physcus flaviventris How., all 

 prey upon this pest. 



THE YELLOW SCALE 



Vhrysomphalus dtrinus (Coquillett) 10 ' 

 (Aspidiotus dtrinus Coquillett) 



(Fig. 161) 



Description. — The scales are circu- 

 lar with rather rough and irregular 

 edges, very flat and decidedly yellow 

 in color. The color and feeding habits 

 serve to distinguish it from the red 

 scale. 



Life History. — The life history is 

 practically the same as that of the 

 red scale, the chief difference being in 

 the feeding habits : the red scale usu- 

 ally attacks the trunks, small limbs, 

 leaves and fruit, while the yellow 

 scale attacks all but the trunks and 

 small limbs. Some county commis- 

 sioners consider this more serious than 

 red scale on citrus trees. "While this 

 may he true in some sections, yet as 

 ;i general films pest it does not seem 

 to be as serious as red scale is in some of the southern coast counties. 



Nature of Work. — This species attacks the leaves and fruit and 



<tv seldom one or two individuals may be found upon the tenderest 



twins. Yellow blotches are produced upon the leaves and the trees may 



Fig'. 161. — The yellow scale, Chrya- 

 omphalus citrinus (Coq.), on orange 

 leaf; .Enlarged twice. (Original) 



■Tlii.--. species is usually considered as a clii latic variety of the red scale, Chrijsom- 

 phalus aurantii (Mask.), from which it is nol structurally distinguishable. 



