216 



APPLIED ENTOMOLOGY 



Jose Scale, the young being born alive during the summer months. Control on 

 citrus trees appears to be best obtained by fumigation with Hydrocyanic acid gas, 

 but with deciduous fruit trees the lime-sulfur wash may be used. 



Occasionally the lenticels or breathing pores through the bark of 

 plant twigs resemble armored scales, particularly the more circular 

 ones. To determine in any case whether a debatable structure on bark 

 is a scale or only a lenticel, it may be scraped with the finger nail. If it 

 can be removed without breaking the bark (it may leave a whitish mark) 



the object is a scale, but if the bark is neces- 

 sarily torn or broken to get it off, it may be 

 assumed that it was a lenticel. 



Soft Scales 



As a group the soft scales are less injurious 

 than the armored scales. Their rate of in- 

 crease is less, their covering less protective, 

 and their larger size renders them more cer- 



FiG. 211. Fig. 212. 



Fig. 211. — Tulip Tree Scale (Eulecanium tulipiferoe) Cook), about natural size. 

 {Original.) 



Fig. 212. — Black Scale (Saisettia olcce Bern.), aliout natural size. (From Cal. Agr. 

 Exp. Sia. Bull. 22.3.) 



tain to be reached by sprays. The largest one found in the United States 

 is the Tulip Tree Scale, the adult female scale being about one-third of an 

 inch in diameter (Fig. 211). An African soft scale is known which is 

 about an inch long. 



The Black Scale {Saissetia olece Bern.). — This scale is found in nearly all 

 parts of the world. It has a long list of food plants but is chiefly a pest on citrus 

 trees and the olive, oleander, apricot and prune. In the United States it is 

 therefore chiefly important in the South and West. The adult female scale is 



