BEET FLY. 61 



The same happens with the maggots of the Celery 

 or Parsnip Fly, and of some of the Turnip leaf-miners, 

 which feed hetween the two sides of the leaf; and also 

 to a great extent with the Beet Fly (Fig. 45). The 

 pupte of these are, respectively, either entirely or to 

 some extent, to be found in the ground near the 

 attacked plant ; and this is one reason of the great 

 use of rotation of crops as a means of prevention. 



Where there has been an infested crop in autumn, 

 there will be many of the pupa-cases in the earth ; 

 when spring comes the Flies crack their way out of 



Fig. 4u.— Beet Fly and pupa, ma^'. and nat. size ; cluster of eggs, 

 magnified. 



their husks, or puparia, and then are all ready to lay 

 their eggs on their own food crop, if it is on the same 

 place, or near. This is an important point in field 

 Cabbage growing, where Cabbage crops are often 

 repeated time after time, and also in Onion and Carrot 

 growing. We may bury many of the pupa-cases, just 

 as we can bury Daddy Longlegs or Wheat-midge grubs, 

 but we must be even more careful not to bring them 

 up again before the time for the Fly hatching out of 

 them has passed, for the cases are firm and strong, 

 and the Fly within them is so well protected that it will 

 bear a deal of burying, and moving about, without any 

 damage. 



