318 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



by spraying it while young with iron sulfate, 2 pounds to 1 

 gallon of water. 



Late-planted cabbage is but slightly affected as compared with 

 that planted earlier. The earliest radishes are often quite free 

 from the pest, those planted later and maturing just as the flies 

 are abundant are badly injured, and the later plantings are free 

 from injury. 



It is evident, therefore, that where planting of the main crop 

 can be delayed until after most of the flies have oviposited, that 

 it will escape serious injury. Furthermore, either cabbage or rad- 

 ishes may be used as a trap crop, by planting a few rows early 

 and as soon as the flies have laid their eggs on them, plowing 



them under deeply and then set- 

 ting the main crop. All of these 

 methods involve a familiarity with 

 the fly and its eggs which any ob- 

 servant grower may soon acquire. 

 High fertilization with a quickly 



FIG. 267. Cabbage maggot, side available fertilizer will enable the 

 view, enlarged, hair line repre- 

 sents natural size; a, view of plants to make a rapid growth and 



StaUST^ head-^ ^ be profitable even if maggots 



enlarged. (After Slingerland.) do not occur. 



Thorough and frequent cultivation while the eggs are being 

 laid destroys many of them. Indeed, one of the best means 

 of control, which is extensively practiced by many growers, is to 

 hill up the earth around the young plants when set, and as soon as 

 eggs are laid, pull the soil containing the eggs away from the plant 

 into the middle of the row, where they or the maggots hatching 

 from them will be killed by the heat. This involves considerable 

 hand work, but where carefully and intelligently followed is one 

 of the surest means of control. 



Preventives. Where late cabbage is grown the plants often be- 

 come infested in the seed-bed. To avoid this the seed-beds should 

 be covered with cheesecloth. The sides of the frame are made of 

 12-inch boards, across which wires are stretched to prevent sag- 

 ging of the cloth, as the whole must be fly-tight. The cover 

 should be removed a week or ten days before transplanting, so 

 that the plants may harden. If eggs are observed in the seed-bed 

 during this time, transplant at once. 



