56 BRITISH APHIDES. 



papers on Aphis vastator in connection with the potato- 

 blight. 



On the other hand, it is averred that the healthiest 

 vines, as being those possessing the most nutritious 

 sap, are those chiefly selected, and most open to 

 attack. Although soil seems to have but little to do 

 with the evil, the wettest and the most sandy loams 

 are generally the most free from Aphis infection. 



The three chief diseases of the vine arise from the 

 growth of the cryptogamic Oldcum Tuckeri, the 

 injuries caused by the small pyralian moth GEhojphthira 

 pell&riana, and this Phylloxera. Besides these, in 

 hothouses we have the grievances caused by mildew 

 and scale. Sulphur, hot water, or tobacco, are cures 

 for these last; but the myriads of Phylloxera vastatrix 

 in great measure have survived all attempts at exter- 

 mination on the large scale. 



M. Lichtenstein states that cavities are sometimes 

 found in the bark of the French vines stuffed full of 

 small black Aphides. These insects do not puncture 

 the vine for its sap, but they have been transported 

 thither, and form the stores of such predatory and 

 minute wasps as Psen, Pemphredon, Cernonus, and the 

 like. 



Prof. Florel, of Lausanne, says that the Phylloxera 

 was introduced into his district through the impor- 

 tation of English vines into the graperies of Baron 

 Rothschild in 18G9. 



It was once thought that this pest could not pass the 

 tropics alive, as the insect cannot bear dessociation 

 from its food for a single week. Its appearance, how- 

 ever, at the Cape of Good Hope, and in also Australia, 

 shows that the eggs will bear considerable dessiccation 

 without injury to their vitality. 



Before giving a diagnosis of Phylloxera vastatrix I 

 would make the remark that every moult which an 

 insect undergoes has its significance, and corresponds 

 to internal changes progressing within the body. It 

 will thus appear how elaborate the history of any 



