TITE BLACK Sl'ALE OF CALIFORNIA. 53, 



(Linn.) is one of the best known and most widely distributed species of 

 Bark-louse. For centuries it has been transported from one country to 

 another, until it lias become thoroughly cosmopolitan and a common pest 

 in green houses throughout the world. In mild climates, like those of 

 southern Europe and the southern United States, it thrives in the open 

 air. It is a general feeder, and although found most constantly upon 

 plants of the citrus family, others in great variety are attacked. Marked 

 preference is shown for plants with smooth bark and thick or glossy 

 leaves; thus the Ivy, Oleander, and Japonica suffer equally with the 

 Orange from the depredations of this Bark-louse. 



THE BLACK SCALE OF CALIFORNIA. 



(Lccanium olece Bernard.) 

 [Fig. 16.] 



The following account of this scale is found in the Report of the 

 Commissioner of Agriculture for 1880, p. 336: 



*' Adult Female. Dark brown, nearly black in color ; nearly hemispheri- 



FIQ. }6.Lfcanium olccz Bernard. 1C, cdult females on Olive, natural size; a, female, enlarged. 

 (AiU-rCumtttock.) 



cal in form, often, however, quite a little longer than broad: average 

 lengih from 4 :nri to 5 imn ; average height 3 mm . Dorsum with a median 

 longitudinal cariua and two transverse cariuae, the latter dividing the 



