THE CABBAGE MAGGOT. ? 



Three out of four niaggots were killed by immersion for one 

 hour in solution of hellebore ( i oz. in i gal. water). 



Observations on Piiparia. The puparia of the last brood, 

 brown cases containing- the pupae, remain in the ground from 

 a half inch to two inches from old stalks, or in the old stalks 

 themselves, or in other debris left in the cabbage field over 

 winter, flies emerging in the spring. 



On May 7th they were found inside the stalk, and among 

 decayed and dried leaves of last year's crop. They were more 

 numerous, however, in the soil near the base of old plants. 

 Near one plant examined on May nth fifteen puparia were 

 found. On June 17th a bunch of twenty puparia were taken 

 from the soil near one cabbage plant. Eight maggots under 

 observation transformed to pupae June 7th. Three of these 

 emerged as flies June 20th, three on June 21st, and two on 

 June 22nd, thirteen, fourteen and fifteen days respectively, 

 after pupation. Another lot of maggots which changed to 

 pupae June 6th, emerged as flies June 19th and 20th (13 and 

 14 days). It may be said then, with reservations, that ordi- 

 narily in Minnesota, the pupal stage of tlie first brood may be 

 from thirteen to -fifteen days' duration., 



Length of Life of Fly. Manifestly observations on this 

 point cannot be made under rational conditions. Flies in 

 captivity have lived in our laboratory three davs without 

 food. 



CHRONOLOGICAL ARRANGEMENT OF THE APPEARANCE OF THE 



DIFFERENT STAGES OF THE CABBAGE MAGGOT FLY 



IN MINNESOTA IN I906. 



May 9 Flies first observed. 



16 Egg laying well started. 

 31 First Maggots observed. 

 June 5 Maggots abundant. 



12 Puparia found in large numbers, and all the cauli- 

 flower of many market gardeners reported de- 

 stroyed. 

 July 7 Nearly all maggots transformed to pupae. 

 Sept. 26 Latest date at which flies emerged from puparia 

 in laboratory. 



