18 



MASS. EXPERIMENT STATION BULLETIN 352 



THIRD GENERATION 



No third generation development has been studied in the insectary. However, 

 from the examination of carrots pulled in October, it was evident that many of 

 the small, partly grown maggots were probably hatched from third generation 

 eggs, and it is the writer's opinion that a third generation of maggots develops 

 in this locality in some seasons. Glasgow (17) also reports a partial third genera- 

 tion in New York State. 



Figure I 



SEASONAL HISTORY OF THE CARROT RUST Fur 



mr JUHC JULY AUCUST SCPT. OCT. 



1 IS 20 25 30 5 10 IS iO is SO S 10 IS lO IS 30 5 10 IS 20 2S 50 S 10 IS ZO 25 iO 5 10 IS ZO Z5 3fl S 10 



IHSeCTARr RECORD $ 



FIELD OBSERrATlON S 



CONTROL 



CULTURAL PRACTICES 



Throughout the study of the life history and habits of the carrot rust fly it 

 has been apparent that the activity of this insect is limited by its environment 

 and that hot weather and dry soil are unfavorable to its development and re- 

 production. Cultural practices can, therefore, be manipulated so as to provide 

 less favorable conditions for the insect and reduce the degree of infestation and 

 damage. 



Legend for Plale 1 



Life Stages of the Carrot Rust Fly. 

 A— Egg X 4.5) B— Larva or Maggot X 7) 

 C~Pupa X 7) D-Adull Fly. Male X 7) 

 E-Adull Fly, Female X7. 



Typical Injury by the Carrot Rust Fly. 

 LEFT-On Carrot; RIGHT-On Celery. 



