DISEASES OF THE OLIVE TREE ] 117 



small beetle, as well as the beetle itself, penetrate 

 beneath the bark and into the wood of the branches and 

 twigs, preferably in the axil of the leaf, or just above a 

 cross twig, producing ramified tunnels killing the bark 

 and seriously injuring the wood. Many small branches 

 and twigs dry up in consequence of this attack, and on 

 the larger branches appear blotches of gum-resin exuded 

 by the tree, which are a sure sign of deep injury. 

 Remove all dead twigs, on which the insect generally 

 lays its eggs, and scoop out the dead and diseased wood 

 from the larger branches, and disinfect the wound by 

 painting it over with liquid tar. 



Among the various scale insects affecting the olive, 

 the worst are the black scale (Lecanium oleae Valk) and 

 the small round white scale (Aspidiotus villosus Targ., 

 which is probably only a form of Aspidiotus Hederae). 

 Both of them multiply prodigiously and exhaust the tree, 

 checking its growth. These scale insects exude a sugary 

 substance which covers the foliage the twigs and branches 

 and affords the necessary feeding ground for the develop- 

 ment of the soot-fungus (Fumago) which imparts to the 

 tree the appearance as if it has been sprayed with a thick 

 solution of soot. This result is particularly noticeable on 

 young trees. The scale insect Philippia Oleae Costa, is 

 rather uncommon, but is met with sparingly everywhere. 

 Spraying with soap and paraffin emulsion or with sulphur- 

 lime mixture is a good remedy against these scale 

 insects; but in bad cases of long standing it is often 

 necessary to prune back rather heavily, towards the 

 close of winter, before spraying, in order to induce the 

 tree to push out strong healthy growth. 



Cases in which the larva of the moth -borer (Zeuzera 

 pirina} tunnels into the branches of the olive-tree, are 

 frequent, but call for no special treatment. 



The worst of the fungous diseases affecting the olive 

 is the "tubercle'' caused by Bacillus Oleae. The tubercle 

 is a cancerous outgrowth on young twigs, branches, stems 



