The Cabbage Root Maggot. 547 



fore in the spring, he forked in a very liberal dressing of coal ashes before 

 sowing radish seed. "The roots produced were nearly or quite as badly in- 

 fested with the maggot as others grown without an application of ashes." 

 Thus there is no evidence that ashes will prevent injury from maggots. 



Bone Dust — This substance has been recommended by various writers since 

 Henderson recorded (" Gardening for Profit") an experiment which simply 

 indicated that fewer plants were injured where a ton of this was used per 

 acre in the spring, than where 75 tons of manure were applied. However, 

 in 1864, a German experimenter found that his bed of Kohlrabi which had 

 been manured with bone dust suffered more from the maggos than the one 

 on which horse dung had been used.* In 1875 {Country Gentleman, p. 

 505) Mr. Philbrick said bone dust does not give the results given by Hender- 

 son. Mr. West {Country Gentleman for 1880, p. 470) also used it at the rate 

 of a tou per acre, and yet lost one-third of his crop of cabbages. Thus 

 the weight of evidence is against the efficacy of bone dust as a preventive. 



Cotton Seed Meal. — In i?t^-] {Rural New Yorker, p. 133), Mr. Hender- 

 son records an experiment by Mr. Geraty of South Carolina who claimed to 

 have secured entire exemption from the maggots by the use of this substance 

 as a fertilizer. We have found no further reference to it. It might be well 

 to test it in localities where it can be profitably used as a fertilizer. 



Superphosphate of Lime. — In i857,this fertilizer was reported as a successful 

 preventive of the Cabbage Root Maggot {^'^Country Gentleman'^-p. 49). In 1864 

 the substance was used in the noted German experiment mentioned above 

 in the discussion of Bone Dust ; in the bed manured with this fertilizer, no 

 plants were attacked. This experiment is the source of most of the recom- 

 mendations of this fertilizer. In 1877, Garfield of Michigan reported that he 

 treated alternate rows of turnips and radishes with it, hoping that its vile 

 smell would prevent egg-laying ; it proved a failure. If it has any preven- 

 tive qualities, which we doubt, it should receive the immediate attention of 

 some investigator. 



{e) Change 0/ Location, or Rotation 0/ Crops. 



JNIany writers have advised that the location of the crop be changed every 

 year or two, thus keeping it out of the way of the insect. But, as Prof Cook 

 says, it would be necessary to move it at least yi. a mile away, which is not 

 often practicable. When it can be done, doubtless good results will often 



* This experiment is referred to by Dr. Lintner and Miss Ormerod as haviug been made 

 by the Zoolog-Botan. Society of Vienna, which, if true, would give it great weight. But 

 the facts are that it was simply recorded in the proceedings of that society for 1864 by Mr. 

 Kiinstler to whom it was reported by Baron Hohenbruck. The experiment was evidently 

 on a small scale, and Mr. Kiiastler concludes as follows: " It does not occur to me to 

 wish to deduce, from this single result, the value of any of the named manures in view of 

 an eventual efficiency against the attacks of the insects ; I present this case only to urge 

 the farmers to make observations in this direction with manure experiments. 

 An effective and practicably applicable means of lessening this pest, no one as yet knows." 

 The species experimented upon was determined by Frauenfeld and Schiner, from the 

 pupae, as Anthomyia radicum. 



