THE GREEN PEACH APHIS. 7 



One remarkable fact about these Peach Aphides, and 

 which others besides myself have doubtless observed, is 

 that in some of the old gardens in the city large peach 

 trees, which may have been planted in the early days of 

 the colony, would appear, upon a very careful examination, 

 to be nearly free from blight of any kind, and, as fruit is 

 occasionally borne, the tree would seem to be healthy. 

 Here is a problem for our savants to solve. Why are these 

 trees, which certainly show no signs of superior cultiva- 

 tion, so clean, whilst others, on highly-cultivated land, 

 and which are very old trees, are often badly attacked 

 and killed by these aphides ? In this connexion it may be 

 interesting to note that the soil in the city is generally of 

 a very stiff and heavy nature, with a firm, hard, and often 

 stony subsoil, and a knowledge of these facts may help 

 us to unravel this mystery, and would appear to point to 

 the heavy tenacious soil as one of the principal causes of 

 the trees' immunity from insects of this kind. In another 

 part of the present number an account is given of an 

 implement by which bisulphide of carbon may be injected 

 into the soil. This machine is fully explained, and, it is 

 hoped, may prove as successful as has been represented. 

 Once we can master the pests at the roots, success as to 

 the other pests, if carefully attended to, will be sure to 

 follow. 



