29 



In view of the extraordinary abundance- of the black scale it is sur« 

 prising that until very recently the male insect had not been discovered, 

 in spite of the most careful search for it. What we know of this stage 

 is due to Dr. B. W. Griffith, of Los Angeles, Cal., who has found the 

 male scales on oleander, orange, lemon, pepper, and iv}^ leaves between 

 the months of November and April, in Los Angeles County. The 

 accompanying illustrations of this sex (fig. 20) are based on material 

 furnished by Dr. Grifiith. 



The natural enemies of the black scale promise to be very efficient 

 in its general control and warrant special notice. They include both 

 the parasitic flies and various species of ladybirds. 



^^^,C^ 



Fig. 21.— Imported lady- 

 bird enemy of black scale 

 {Rhizobius ventralis) : a, 

 mature beetle; b, larva— 

 both greatly enlarged 

 (author's Illustration). 



Fig. 22. — Imported chalcidid parasite of black scale 

 (Scutellista cyanea), dorsal and lateral views — ^greatly 

 enlarged (after Howard). 



The ladybird enemy of special importance is the Ehizobim ventralis, 

 imported by Mr. Koebele. This ladybird (fig. 21) has been colonized 

 in various parts of California, and in districts where the climatic con- 

 ditions proved favorable its work has been most satisfactory, notably 

 on the ranch of Hon. Ellwood Cooper, at Santa Barbara. Hundreds 

 of thousands of these beetles have been distributed in southern Cali- 

 fornia and have accomplished in some localities a very great deal of 

 good in keeping the black scale in check. Away from the moist coast 

 regions, however, it is less effective, and experience has shown that this 

 ladybird can not be completely relied upon to control the black scale. 



172 



