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VII. — Observations on the Natural History and Economy of 

 various Insects affecting the Turnip- Crojjs ; including the 

 Plant- Lice, M^ig^otsof Flies, Catermllars of Moths, c^-c. 



^ By John CurtisTT^.L.S., Corresponding MemUer of the 

 Imperial and Royal Georgofili Society of Florence, &c. 



Paper III. 

 Having detailed the economy and natural history of two of the 

 most formidable enemies to the turnip-crops, I shall proceed to 

 the investigation of some others which attack the folia2:e, and 

 leave for a future report those which assail the roots. Some of 

 them may at first appear to be of little consequence, as affecting 

 the property of the farmer; but as we know that it is only from 

 the excess of insects that serious mischief arises, and as it is far 

 from improbable that they may all have their destined periods of 

 appearance, to ravage our crops with fearful force^ none of them 

 ought to be neglected : for these reasons it will be advisable to 

 make all the insects connected with farming known to the agri- 

 culturist ; and I hope that the thirst for knowledge which is so 

 natural to man will tend to render my investigations acceptable. 

 Let it likewise ever be borne in mind that whatever God has 

 created is deserving of our attention, and the more we study his 

 works the more convinced shall we be of the wisdom they mani- 

 fest. 



History of the Aphides, or Plant-Lice. 



There is no tribe of insects so universally distributed, or ex- 

 ceeding in multitudes the plant-lice ; and, of all the animals that 

 are destined to torment the gardener, none are more successful 

 than the Aphides, and the agriculturist not unfrequently suffers 

 from the effects of their blighting powers, for probably there is 

 not a plant, from the smallest grass to the most stately tree, that is 

 altogether exempt from the visits of this pigmy : — 



" Feeble race ! yet oft 

 The sacred sons of vengeance, on whose course 

 Corrosive famine waits, and kills the year." 



The immortal Linnaeus, considering that every plant supported 

 a distinct species of Aphis, named these insects after the vegeta- 

 bles they fed upon ; and similar as they may appear to a careless 

 observer, I am induced, from an extensive and careful examina- 

 tion of this subject, to subscribe generally to the opinion of the 

 Swedish naturalist : indeed, as far as the turnip is concerned, 

 there are three, if not four, species of plant-lice that are attached 

 to the different varieties of this invaluable crop — two or three 

 living upon the leaves, the other infesting the flower-stalks of 



VOL. III. E 



