512 



Bulletin 78. 



destructive ; but we believe it appears every year, in greater or less num- 

 bers, in all localities. Even in Canada, early cabbages are sometimes injured 

 in the seed bed, says Mr. Fletcher. 



The first brood is well defined ; the flies appear in April and 

 their maggots work destruction in May on the roots of the cab- 

 bage tribe, on radishes, and on turnips. The time when the first 

 brood of maggots mature will of course vary with the season. 

 This year, on lyong Island, they matured about June i, changed 

 to pupae, and a majority of the flies had emerged by June 15. 

 This date agrees closely with the recorded rearings of the flies 

 from maggots of this first brood. Thus the second brood begins, 



Fig. 10. — Cage devised /or breeding the Cabbage Root Maggot. 



in New York State, with the appearance of these flies about June 



15. It should be borne in mind, however, as recorded above, 



that all of the puparia of the first brood do not give out their flies 



in June ; some do not appear for months after. Our observations 



indicate that at least 75 per cent, of the flies appear in June. 



Although hundreds of these flies emerged in our large cages prepared 

 especially for their comfort, none laid eggs, all dying in a fev? days. One of 

 these cages is shown in figure lo. It consists of a framework covered with 



