538 Bulletin 78 



spoonful of the liquid was applied beneath several plants with the 

 injector. In a few minutes the odor of the liquid was very notice- 

 able on the surface around the plants. These plants have not 

 showed any signs of injury from this large dose. As stated in the 

 description of figure 17, the amount of liquid to be applied can be 

 easily regulated. On small plants, a teaspoonful will probably be 

 sufficient. When the plants are well established in the field, and 

 the maggots thick, use a tablespoonful. One application will 

 usually suflSce. The time to apply will be when the maggots are 

 first discovered, early in May. Do not wait until the plants begin 

 to wilt before making the application, for although it will then kill 

 the insects, it will not reinvigorate the plant. 



We believe gardeners will find this the most practicable and 

 most effective method of killing the Cabbage Root Maggot when 

 it attacks cabbages and cauliflowers. 



2. DOUBTFUL, OR PARTIALLY EFFECTIVE METHODS. 



With some gardeners, many of these methods may prove quite 

 effective ; in fact some have used them with apparent success. 

 However, we believe that they should be more thoroughly tested 

 before they are unqualifiedly recommended for indiscriminate use 

 by gardeners. 



A. PREVENTIVE. 



/. Substances Applied to the Soil. 



Gas Lime. 



Doubtless the vile-smelling properties of this refuse from gasworks, is what 

 suggested its use as a preventive of the Cabbage Fly. However, evidence ac- 

 cumulates every year that vile smells are not so obnoxious'to insects as was 

 thought several years ago. Prof. J. B. Smith showed (Bull. 75. N. J. Expt. 

 Station, p. 29) that gas-tar has no repellant effect on the Squash Borer. He 

 also says (Bull. 85, p.8) that "it is important to know that what we consider 

 as foul or vile smells never yet kept away insects. ... It is not the 

 smell of gas lime, but the caustic properties that are of value " Mr. Lazen- 

 by found (Mich. Hort. Soc. P.eport for i88r, p 2i_i) that gas-lime did not 

 effectively repel the Codlin Moth. 



The first record we find of the use of gas lime to prevent this pest, is by 

 Mr. Garfield in 1877. He treated alternate rows of r.idishes and turnips 

 with the substance, "hoping by means of a vie odor to prevent the flies 



