26 MASS. EXPERIMENT STATION BULLETIN 412 



Planting experiments at Waltham indicated that fast-growing radishes of the 

 Scarlet Globe type, which mature in about 30 days from the time the seed is 

 sown, can be grown with little injury from the cabbage maggot between the 

 active periods of this insect. As shown in Table 14, little injury resulted when 

 the seed was sown from May 25 to June 5, or after July 10. Although no seed 

 was sown before May 1, radishes planted before April 10 should escape serious 

 injury; but those from seed planted between April 15 and May 1 would be heavily 

 infested. Under eastern Massachusetts conditions, early radishes must be pro- 

 tected by a cheesecloth screen after May 10 to avoid injury by the cabbage 

 maggot. 



Table 14. Relation of Date of Planting Cavalier Radish to Injury by 

 THE Cabbage Maggot. Waltham, Massachusetts, 1938-1939. 



Percent of Radishes Infested Percent of Radishes Infested 



Date Seed Date Seed 



Sown 1938 1939 Average Sown 1938 1939 Average 



May 1-2 37 29 33.0 June 30-July 2 12 30 21.0 



May 10-12 16 45 30.S July 10-12 1 5 3.0 



May 20-23 12 42 27.0 July 20-25 3 2 2.5 



May 29-June 2 . . . 5 2 3.5 August 2 — 0.0 



June 10-14 18 59 38.5 August 15 2 — 2.0 



June 20-22.... . 44 44 44.0 .'August 30 — 15 15.0 



September 10 — 4 4.0 



SUMMARY 



The cabbage maggot, a native of Europe, is now well established in North 

 America, where it is a destructive pest of cruciferous plants in the cooler regions. 

 It belongs to the family Anthomyiidae and is nanaed Hylemya hrassicae Bouche. 

 The egg, larva, pupa, and adult stages are briefly described and illustrated. 

 There are three generations annually, of which the first is the most destructive 

 to early cabbage and similar crops, while the third often damages late turnips 

 and radishes seriously. 



It attacks all cruciferous plants and has been reported feeding on celery and 

 beets. The relative susceptibility of the common cruciferous vegetables is shown, 

 and experiments to determine resistance among cabbage varieties, in which 

 Early Jersey Wakefield has been outstanding, are reported. 



Injury to plants is caused by the feeding of the maggot, and badly infested 

 plants become gray in color, wilt, and usually die. Moderately infested plants 

 may recover in cool weather by developing secondary roots as illustrated On 

 radish, turnip, and kohlrabi, in which the root is edible, slight maggot injury 

 makes the plant worthless. 



Rotation of cruciferous crops, fall plowing, and similar cultural practices reduce 

 the losses from this pest; and all cabbage stumps and infested turnips, which 

 are the source of spring infestations, should be destroyed before winter. 



Control treatments, to be successful, should be based on the activity of the 

 insect. In these studies they have been correlated with the time when the first 

 eggs were laid, which occurred between April 29 and May 10 in the thirteen->ear 

 period, 1931-1943. 



