NATURAL HISTORY OF SOUTH AFRICA 



exhales oxygen. The majority of trees die if deprived 

 of all their leaves. I have seen patches of forest 

 blasted and dry as though stricken by a fierce wave 

 of heat. I watched an army of caterpillars kill a 

 noble old oak tree in Pietermaritzburg. They began 

 at the top of the tree and, eating many times their own 

 weight of leaves each day, they, in the course of two 

 weeks, stripped it absolutely bare of foliage. Then, 

 descending to the ground in the night, they migrated 

 to another tree and blasted it also. A few birds made 

 daily assaults on this mighty host, but alas ! they 

 were but the attenuated remnant of a once strong 

 army of defence. The human folk in their blindness 

 had succeeded in almost exterminating their allies. 



Battalions of gall-flies attack the twigs and form 

 galls upon them. Weevils bore into the pith and 

 lay eggs which hatch into grubs. The cicada, or 

 " Christmas bee," inflicts wounds in trees, often of a 

 serious nature. Aphides, scale insects, and plant lice 

 weaken the tree by sucking its juices, which are to it 

 what blood is to us. The grubs of great numbers of 

 species of moths feed upon the buds and flowers. 

 Preyed upon by such hosts of enemies, the tree grows 

 increasingly weak and becomes a prey to parasitic 

 plant growths such as fungi ; and the terrible white 

 ant or termite attacks both roots and trunk of the 

 harassed and sickly giant. 



Such are the enemies which prey upon forest 

 trees ; enemies which, if not kept sternly in check, 

 would multiply in an incredibly short while and 

 sweep the forests out of existence. And without 



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