148 



INSECTS INFESTING THE OLIVE. 



between the time of the first formation of the calcareous secre- 

 tion by which the insect is covered, and their reaching matur- 

 ity or becoming fixed to any part of the plant. 



Fig. 122. 



Fig. 122. — Hhuk Scale; /, an infested twig; la, side view 

 of one of the scales, enlarged — color, dark brown. 



In relation to this smut or fungus, Professor Barlow writes : 

 " The result of our examination of the diseased orange and 

 olive leaves is briefly as follows : The disease, although first 

 attracting the eye by the presence of the black fungus, is not 

 caused by it, but rather by the attack of some insect which 

 itself deposits some gummy substance on the leaf and bark, or 

 so wounds the tree as to cause some sticky exudation on 

 which the fungus especially thrives. It is not denied that the 

 growth of the fungus greatly aggravates the trouble already 

 existing by encasing the leaves, thus preventing the action of 

 the sunlight. We only say that in seeking a remedy we are to 



