INSECT ENEMIES. 259 



may frequently see, on closely observing the leaves, little 

 faded patches, with a minute brown speck in their centres. 

 On examination with a good glass, these are seen to be the 

 pupse of a small fly, the Phytomyza nigricornis, the same 

 as that which infests the turnip leaves, the larvse feeding 

 on the "parenchyma," or fleshy part 'of the leaf, and sadly 

 injuring it and interfering with its functions. As their 

 growth advances too, just at the time of flowering, they 

 are liable to be attacked by the Aphis pi si, " pea-aphis/' 

 or "green dolphin/' as it is sometimes called, to distin- 

 guish it from the aphis infesting the bean plant. These 

 commit, in some seasons, great ravages in the crop, and 

 although not generally so serious in their results as the 

 attacks of the "bean- aphis/' still the effects, on the whole, 

 are equally felt, as, owing to the trailing habit of the pea, 

 the same treatment there recommended cannot be admin- 

 istered, and the plant has to sustain the full brunt of their 

 attacks. As soon as the pods are formed, they become 

 suitable receptacles for the maggots of certain little flies. 



1. Caterpillar on pea, which it has eaten out. 2. Caterpillar, magnified. 

 3 and 4. Moth (Tortrix pisana), natural size and magnified. 



Then the caterpillars of a moth (Tortrix pisana) live 

 upon the young green seeds (peas) in the pod, render- 

 ing them "maggotty" at harvest- time, and injuring the 

 whole sample. These worm-eaten peas, when thrashed 

 out, are infested by the Tinea sarcitella (the white- 



