EXTERMINATION OP THE HOP APHIS. 187 



deficiency of wages, &c, are thought to have sustained 

 at least £200,000. 



The advice I here would give is to burn the vines 

 immediately after the hops are picked ; watch for the 

 foundress as she rises from the soil, and takes to the 

 young plant when it is only a few inches high ; wash 

 thoroughly, by hand at first ; and in February or 

 March, on a sufficiently large scale ; and use the same 

 means as our friends on the other side of the English 

 Channel use to stamp out the Phylloxera. 



There is yet another consideration I here offer to 

 those most interested in destroying Plwrodon humuli. 

 As this species feeds on the green leaves, and has not 

 been shown to be dependent on the root of Humulus 

 lupulinus for its sustenance at any time, the life- 

 cycle is complete in a single year. Therefore, if by 

 mutual consent, no hops are grown (for say three 

 years) on a district so wide that the winged insect 

 is not likely to traverse it, a large portion of this area 

 would be free from Aphis for an indefinite time. 



There can be no doubt that, as rapid locomotion and 

 ready transit transplant fresh species of insects, into 

 new localities, so isolation will be a chief factor in 

 stamping them out. 



In connection with the economy of Plwrodon humuli, 

 I will here state that, through the kindness of a friend 

 living at Staplehurst in Kent, a block of earth, con- 

 taining the root-stock of a hop plant which had been 

 infected with fly during the previous year, was con- 

 signed to me in March of this year. I spent nearly 

 two hours in investigating the mass, taking a spoonful 

 at a time, and viewing it under lenses of different 

 magnifying powers. I could not find a trace of either 

 Aphis or egg. The earth was rather pale in colour, 

 so if a dozen eggs or even fewer had been present, I 

 believe I should have seen them. A few small centi- 

 pedes and the larva of a small beetle were the sole 

 rewards of my pains. 



This earth from Staplehurst is now reserved for the 



