Insects in the Garden 329 



5 days. The young maggots feed on or within the roots, 

 but when fully grown they usually leave the plants and 

 burrow out into the soil, where they change to the pupal 

 or dormant stage. During the summer months, the 

 pupa lies dormant only from 12 to 18 days, and then the 

 adult flies appear. Thus, several broods are produced 

 in a season. The pupae that are formed in the autumn 

 live over winter in the ground. The following methods 

 are used in the control of the radish maggot : 



(1) Protection by covering. Beds of radishes or cab- 

 bage plants grown in cold frames, or outdoor beds of 

 these plants, may be protected from the flies by placing 

 over them a board frame covered with cheesecloth. 



(2) Prevention of egg laying. It is believed by some 

 that the flies will not lay their eggs in soil upon which a 

 little kerosene has been sprinkled. To apply the kero- 

 sene, pour a cupful of it over a pail of dry sand, mix well, 

 and scatter the sand over the soil about the plants. 



(3) Disks of tarred paper. Cabbage plants may be 

 protected by covering the earth about the roots of the 

 plant with disks of tarred paper about 4 inches in diam- 

 eter. These should be fitted closely about the stem of 

 the plant when it is placed in the field. 



(4) Killing the maggots in the soil. The maggots that are 

 in the soil may be killed by pouring kerosene emulsion or 

 corrosive sublimate solution (i part of corrosive sublimate 

 to 1000 parts of water) over the bed or row until it soaks 

 down into the soil about the main roots of young plants. 

 Another effective solution, which may be used in the 

 same manner, is made as follows : mix a pint of crude 

 carbolic acid in a gallon of hot water, then add a bar of 



