THE CABBAGE MAGGOT 7 



CONTROL 

 General Precautions 



All cultural practices which reduce the number of cabbage maggots in an area 

 where cruciferous crops are grown are important. 



On early plantings one of the recommended control treatments should be 

 carefully applied, and if two plantings of the same or related crops are made 

 annually, the second crop should be planted at some distance from the field 

 where the early crop was grown. 



On late crops of cabbage and cauliflower, the cabbage maggot is seldom a 

 destructive pest, but the third generation of this insect develops almost entirely 

 in the roots of the late crops and becomes the source of flies for the following 

 spring generation. On late crops of turnips and radishes, however, the third 

 generation of the cabbage maggot may be very destructive and abundant. The 

 stumps of cabbage, cauliflower, and broccoli may harbor large numbers of cabbage 

 maggots, as shown in Table 3; and even though worthless, these stumps should 

 be gathered and destroyed and the soil plowed just before the ground freezes. 



Table 3. Number of Cabbage Maggot Pupae Collected in Ten 



6X6X6 Inch Soil Samples Around Overwintered Host Plants. 



Waltham, Massachusetts, April 18, 1941. 



Relation of Biology to Control 



Any insecticide or repellent applied for combating this insect must be active 

 when the flies are laying eggs or when the maggots are hatching and beginning 

 to feed. Therefore, the application of control measures must be timed according 

 to the biology and development of the insect. The treatments discussed in this 

 bulletin should be begun at the time or just before the first eggs are laid and 

 should give protection during the hatching period of the larvae; hence it is neces- 

 sary to know the time when these activities occur for successful application of 

 control measures. A knowledge of the seasonal biology of the cabbage maggot 

 is particularly desirable since injury by this insect is seldom apparent until after 

 the infestation has become established and the greater part of the damage to 

 the plant has been done. Then the pest can be controlled only with great diffi- 

 culty, if at all. 



In Geneva, N. Y., Glasgow (5) determined that the first flies appeared about 

 the time the Windsor cherries and the Reine Claude plums were in full bloom. 

 At Waltham no records of the appearance of flies have been made. However, 

 careful records show that the first eggs have been laid in the field during the 

 twelve-day period April 29 to May 10, and that the first eggs have been found 

 in the six-day period May 5-10 in ten of the thirteen years when observations 

 were made. 



