850 BLIGHT. 



tude of small, wingless creatures, which are busily 

 employed in preying upon the limb of the tree 

 beneath. This they are well enabled to do, by 

 means of a beak terminating in a fine bristle (Plate 

 5, Fig. 3) ; this being insinuated through the 

 bark, and the sappy part of the wood, enables the 

 creature to extract, as with a syringe, the sweet, 

 vital liquor that circulates in the plant. This ter- 

 minating bristle is not observed in every individual : 

 in those that possess it, it is of different lengths, 

 and is usually, when not in use, so closely concealed 

 under the breast of the animal as to be invisible. 

 In the younger insects it is often manifested by 

 protruding like a fine termination to the anus ; but 

 as their bodies become lengthened, the bristle is not 

 in this way observable. The alburnum, or sap 

 wood, being thus wounded, rises up in excrescences 

 and nodes all over the branch, and deforms it ; the 

 limb, deprived of its nutriment, grows sickly ; the 

 leaves turn yellow, and the part perishes. Branch 

 after branch is thus assailed, until they all become 

 leafless, and the tree dies. 



Aphides, in general, attack the young and softer 

 parts of plants ; but this insect seems easily to 

 wound the harder bark of the apple, and by no 

 means makes choice of the most tender part of 

 the branch. They give a preference to certain 

 Sorts, but not always the most rich fruits ; as cider 

 apples, and wildings, are greatly infested by them, 

 and from some unknown cause other varieties seem 

 to be exempted from their depredations. The 



