Mr. CoRTis's ObfervatioHs on Aphides. 77 



relative to their hiftory, and to make them more generally known, 

 will not, wc truft, be unacceptable to the public. Such inquiries 

 may poflibly lead to the means of obviating the injuries they occa- 

 fion ; and if they fail in this, they may tend at leaft to correa the- 

 erroneous notions entertained of blights, not by the vulgar and illi- 

 terate merely, but even by pcrfons of education, who may frequentfy 

 be heard to maintairt that thele infeas are brought by the eaft winds ; 

 that they attack none but fickly plants ; with other notions, all as 

 falfe in fa61: as unphilofophical in principle. 



Locufts and caterpillars, famed for their devaftations, are fur- 

 niihed with ftrong jaws, by means of which they crop and wholly 

 devour the foliage of plants. The Aphis dellroys them in a different- 

 way. Inftead of jaws and teeth it is provided with a hollow-pointed 

 probofcis or trunk, which, when the animal is not feeding, folds 

 under its bi eaft. With this inftrument it piercesthe plant,, and^ 

 imbibes its juices to fupport itfelf ; but thefe juices- being eflential to 

 the life of the plant, it follows that, when they are drawn off, 

 the plant,, exhaufted,- flags and perifhes, being in fail literally bled 

 to death by thefe leech-like animalcules^ Yet, fo tenacious of life 

 are plants in a healthy ftate, that they in general only fall vidims; 

 to the continued attacks of thefe infeds when in immenfe numbers. 

 But it moft commonly happens that if they do not wholly deflrcy. 

 a plant they deface it, and a fmall number of Aphides are fufficient 

 to produce this effedt. The leaves of fuch trees and plants as have 

 a firm texture and ftrong fibres, though infefted with thefe infers,, 

 preferve their form ; but the more tender foliage of others, and 

 flowers in general, cannot bear their punctures without curling up' 

 and becoming diftorted ; in confequence of which they lofe their 

 beauty entirely and irretrievably. The cultivators of plants, efpeci- 

 ally in ftovesand green-houfcs, cannot be too much on their guard 

 againft the whole tribe, of Aphides', for with what pleafure can a. 



large. 



