INSECT ENEMIES. 



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hibit signs of injury, occasioned by a minute fly, of a pale 

 slate colour, the Phytomyza nigricornis, or an equally 

 small fly, of a pale green colour, called the Drosophila, 

 ftava "yellow turnip-leaf miner " which lay their eggs 



1. Blistered surface of leaf. 2 and 3. Maggot (natural size and magnified). 

 4 and 5. Pupa) (natural size and magnified). 6 and 7. The fly, Drosophila 

 flava (natural size and magnified). 



upon the leaves, the maggots when hatched burrowing 

 and making galleries between the cuticles, living upon the 

 fleshy part (parenchyma), and thus destroying its impor- 

 tant functions in the processes of vegetable life. Later in 

 the autumn the turnip plant-lice Aphis brassicce and A. 

 rapce are met with, swarming on the leaves and abstract- 

 ing their nourishment from them, and adding to the 

 amount of injury they have already sustained. 



This brief sketch of the better-known insect enemies the 

 turnip has to encounter in its passage through life, must 

 suffice here ; full details of their natural history will be found 

 in the interesting pages, already alluded to, of Curtis, Kirby 

 and Spence, Kollar, and other writers on entomology. 

 Their ravages are far greater, and the injuries they inflict 

 far heavier, each year, than we usually, from our general 

 want of observation, and indeed ignorance, of their exis- 

 tence or habits, believe ; it is only when the attack of any 

 one of them is very marked, as of the "black nigger" in the 

 past season, that we find much notice bestowed on them, and 



