48 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION 



The best time to kill the scale is during the period just following 

 hatching, usually in August and September, but fair results may be 

 expected at any time from the middle of August to the first of 



January. 



The proper quantity of material should be applied in the form 

 of a rather coarse driving spray under a pressure of from 100 to 200 

 pounds. For the average-sized tree from five to seven gallons should 

 be sufficient to thoroughly cover every portion adequately. 



A sufficient number of scales to produce any noticeable amount of 

 honeydew and cause a corresponding degree of smutting should be 

 sufficient evidence to warrant spraying. 



In spraying an orchard, it is important to keep the following in 

 mind: 



1. In case of doubt as to the strength of materials to use, spray a 

 few trees to ascertain results before treating the entire orchard. 

 Allow about two weeks to get the full results of the chemicals. 



2. Never spray when the orchard is in need of water, as severe 

 burning of fruit and foliage may result. Irrigate first or wait until 

 after the first rain. 



3. Do not spray during excessively hot weather or when hot winds 

 are blowing. 



4. Do not spray within several weeks before picking, if possible, as 

 spotting of the fruit may result. 



The control of the black scale by natural enemies has long been 

 the subject of much experimental work without any very definite re- 

 sults. True, a number of predaceous and parasitic insects have been 

 introduced to combat it, but their combined efforts are not sufficient 

 to be a reliable factor in the control of the pest in the orchards. 



The predaceous insects include the following: 2 the black ladybird 

 beetle, Rhizobiiis ventralis Er., the ashy-gray ladybird beetle, Olla 

 abdominalis (Say), Lindorus lopanthae (Blaisd.), the steel-blue lady- 

 bird beetle, Orcus chaly'beus (Boisd.) and Axion plagiatus Oliv. Of 

 these, the first is the only one of importance. It was first introduced 

 into the olive orchards of Santa Barbara County and has since been 

 distributed generally throughout the state. The larvae and adults 

 feed upon the black scale and in some districts become quite abundant. 

 Lindorus lopanthae (Blaisd.) is also quite widely distributed and 

 preys partially upon the black scale. The others seem never to be- 

 come very numerous or important. 



2 For a complete list, discussion and illustrations of predaceous and para- 

 sitic insects of the black scale, see Bui. 223, Calif. Agr. Exp. Station. July, 1911, 

 by Prof. H. J. Quayle. 



