532 Bulletin 78. 



it would not do effective work in clay soil, or that it killed 

 the plant, had, without doubt, deferred the application till 

 the plants were beyond hope. A Mr. lyCe, in the audience, 

 said he had tried the liquid, and knew it would always work on 

 clay or sand, and not hurt the plants. He jjiade a hole a little way 

 from the plant. We italicize this sentence, because it is the key- 

 note of success with this substance. We believe that most of the 

 reported injury to the plants has been due to the hole having 

 been made close beside the plants so that the liquid itself reached 

 the roots. The liquid would very quickly kill the root, but its 

 vapor would do no harm. This point is more fully emphasized 

 later on 



The following year, however, Prof. Cook says he is persuaded, after a 

 thorough trial, that this substance cannot be made practicable. Differences 

 in soils, and seclusion of the maggots which bore quickly out of reach of 

 the insecticide, make its use uncertain, and therefore unsatisfactory. In 

 1888, Mr. Hulst reported that the substance could not be used, for when it 

 came in contact with the roots it always did them very great injury. In 

 1892, in response to an inquiry from Mr. Earnhardt, the U. S. Kntomologist 

 advised him to try the liquid. Although the application was made ( June 15) 

 after many of the maggots had changed to puparia, he reported very satis- 

 factory results. 



From the above brief resume of the experiments thus far 

 reported with this substance, we glean that the weight of evi- 

 dence shows that it can usually be depended upon to kill the 

 maggots. The only serious objections raised are that it some- 

 times seems not to work alike in all soils ; also, it may injure 

 the plants ; and such large quantities would have to be used on 

 radishes, onions, or turnips as to make it expensive and thus not 

 practicable on these crops. The last objection is doubtless a 

 valid one, unless the plants are of a choice or new variety. How- 

 ever, we believe, as did Prof Cook and Mr. Lee in 1886, that 

 when properly applied, it will prove very effective against the 

 maggots on any soils without injuring the plants ; of course, it 

 will work slower somewhat on the heavier soils, and the dose 

 may have to be increased slightly on such soils. 



A few preliminary experiments in cages here at the insectary with this 

 substance showed that it killed, not only the maggots, but the puparia also. 

 Scarcely a live insect could be found in the cages the next day after apply- 

 ing a teaspoonful of the liquid to each plant. Ten puparia were placed 

 beneath the soil in each of two cages, and to one cage a teaspoonful of the 



