12 



BULLETIN 134, U. S. DEPARTMENT OF AGRICULTURE. 



THE BLACK SCALE. 1 



Saissetia oleae Bern. 



DISTRIBUTION AND INJURY. 



The black scale is generally distributed throughout the Mediter- 

 ranean citrus sections. (Fig. 2.) It varies in numbers from an occa- 

 sional scale to numerous specimens forming a complete incrustation on 

 the twigs and branches, and in injury from an insect of no commer- 

 cial importance to one doing much damage through the quantity of 

 sooty-mold fungus found on the trees and fruit. 



In the most important orange section of the Mediterranean 

 countries, that of Valencia, Spain, the black scale is, according to our 

 standards of judging, entitled to rank first among the citrus fruit pests. 

 This statement is at least true for the years 1912 and 1913. In all of 

 the scores of packing houses visited during the month of March, 1913. 



X Represents ffte more /mporfanf 



cffrc/s secf/ons of//ie Afed/ferranean /feg/'or? 



Tr/po/i 

 Saida 

 '/'.ere 

 Jaffa 



Pig. 2. — Distribution of insect enemies of citrus fruits in Mediterranean countries. (Original.) 



from a half dozen to 15 or 20 women were seen washing fruit to remove 

 the sooty-mold fungus occurring as a result of black-scale infestation. 

 In some cases the sooty mold was due to the mealy bug (Pseudococcus 

 citri), but infection from this source would amount to only a small 

 percentage of the total. During July, 1913, when the section was 

 again visited, numerous young were seen on the leaves, which, barring 

 a heavy mortality later, would furnish the same conditions for the 

 season following. In numerous groves around Burriana, Spain, the 

 sooty-mold fungus was seen to form a complete coating over all the 

 upper surface of the leaves, branches, and fruit, and such a severe 

 incrustation of scales occurred as actually to kill many of the smaller 

 twigs, and in some cases even the larger branches. 



The greatest injury from the black scale was seen in the "Plana," 

 or level district opening to the sea north of Valencia, and centering 

 around Burriana. The conditions here are much the same as in the 



Spanish, Escania negra; Italian, Cocciniglia dell' olivo. 



