XXX11 INTRODUCTION. 



evidence which I have collected. They will have to 

 traverse, as I have done, many miles to procure it, 

 especially with relation to its existence in the rarer 

 plants. It ' is only where the insect excessively 

 abounds that many of the plants are affected ; and so 

 numerous are the creatures sometimes, that I have 

 taken a lid of a pill-box, and scooped up half a box 

 full of the winged creatures from a single leaf of the 

 beet plant. Their number in some cases has ex- 

 ceeded all description ; and there was a little field in 

 the Old Kent Road, surrounded by houses, which 

 presented a wonderful living mass of these creatures. 



The migratory habits of the insect will sometimes 

 perplex the investigator ; for, upon searching over a 

 tract of land, he may find none of these creatures ; 

 yet, upon a more careful scrutiny, the ichneumoned 

 remains which are still to be seen adhering to the 

 leaf, will benr sufficient testimony of the previous 

 existence of the destroyer. 



The examination of the plants for the Vastator 

 may be performed with the naked eye, though the 

 more minute investigation of the insect itself doubt- 

 less requires a glass. The agriculturist should pro- 

 cure a small pocket glass, with lenses of three focal 

 distances, which he can procure for five shillings. 



He should also possess a microscope of higher 

 power, to examine more minutely the parts of insects. 

 These can be bought for twenty-five shillings, but 

 I should certainly recommend him not to give less 

 than five guineas for an instrument. I have carefully 



