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and mealy bugs (Ccccidae). These are all minute insects that 

 suck the juice through the slender tube which is inserted into the 

 tissues of the plant. Instances of this form of attack are suffi- 

 ciently familiar, though the cause is not always recognized. 



Trees are commonly to be found covered with "black blight", 

 that is, the upper sides of the leaves are coated with a black layer 

 like soot. It is often thought that this is a serious disease at pre- 

 sent, but it is not the black blight. If the underside of such a leaf be 

 examined, either mealy-bug will be found or small rounded insects, 

 (scale insects). These are the real pests, the black blight being 

 merely a secondary result. A plant with black blight will be found 

 to have scale insects on the leaves or branches, or else a neigh- 

 bouring tree is thus infested. Black blight, in itself, does little 

 harm, it is a fungus that lives on the sweet excretion dropped by 

 the scale insects and may be regarded as an indication of the more 

 serious disease. When the scaie insects are destroyed, the black 

 blight will in time disappear also, and the plant will regain its 

 normal vigour. 



Scale insects may be found on any part of a plant, some attack- 

 ing the roots, others the stem, branches, leaves or fruits. Other 

 sucking insects occur, but they are usually of far less importance. 



Preventive Measures. 



Before discussing what remedies to apply, it may be of use to 

 consider how to guard against the attacks of insects and other 

 pests. The point of greatest importance is to maintain the vigour 

 of the plant, to keep it in as healthy a condition as possible and 

 never to allow it to become weak. Plants are particularly liable to 

 disease when thay lose vigour, as in time of drought. An addition- 

 al preventive is to ensure the absence of weed, and of decaying 

 vegetation of any kind. Rotting fruits, trunks or branches offer a 

 convenient home to many undesirable insects, and should be dug 

 in, when possible, or removed. If disease comes, it is essential to 

 check it at the outset. A pest should never be allowed to become 

 established, vigorous measures should therefore be taken as soon 

 as it is observed. A small amount of trouble at the beginning may 

 save much labour afterwards, and may preserve the crop from in- 

 jury. It is most important to be always on the watch for signs of 

 injurious insects, and, as soon as they are seen, to adopt immediate 

 and thorough measures for their destruction. 



Remedies. 



Insects may be destroyed in two ways (1) by catching them and 

 (2) by poisoning them. For boring and leaf-eating insects both 

 methods may be used, for sucking insects the latter only, as a rule. 

 In applying these remedies, it must be remembered that many 

 insects pass through three stages. From the eggs comes the cater- 

 pillar (worm) or grub, which is usually the destructive stage. 

 After this has attained its full size and stored up fat, it transforms 

 itsell into the chrysalis or pupal stage. This is a resting stage, 

 often passed in a coroon or other covering, in or on its food plant, 



