408 Report of the Department of Entomology of the 



from maggot attack, without injury to the plants. Again, in 1886, 

 Cook 2 tested a stronger solution that contained .44 per ct. of the 

 acid. The insecticidal properties of carbolic acid at this dilution 

 were evident, but the plants were injured wherever it was used. 

 In 1887 Fletcher 3 reports that he successfully protected a crop of 

 radishes from root maggots with the strength of emulsion first used 

 by Cook. Following this experience Fletcher 4 has recommended 

 this mixture many times in his reports. Slingerland 5 employed an 

 emulsion in his tests that contained 0.32 per ct. of carbolic acid. 

 This gave some protection against maggots and did not injure the 

 plants in any of his tests. He sums up his work by saying "we 

 believe it is the most successful and most practical method of treat- 

 ing radishes, turnips or onions yet devised." 



The earlier writers regarded the carbolic acid as a preventive 

 and not a remedy. Slingerland believed, on the contrary, that it 

 was a strong larvicide, and gave a full discussion of the action of 

 the material in his tests. Washburn 6 records, in 1906, some field 

 tests in which he treated cabbage with an emulsion containing 

 0.37 per ct. of carbolic acid. There was very little injury to this 

 field by maggots, so there was no opportunity to observe the effect 

 of the material as a larvicide; but the checks were perceptibly better 

 than the plants treated with the emulsion, and Washburn states 

 that the comparatively poor showing of the treated plants suggests 

 that the carbolic acid may have had an unfavorable effect. In 

 connection with another test he says that the material works injury 

 if applied to very young plants. In 1907 Smith 7 mentions carbolic 

 acid as one of the most effective of all the destructive agents for this 

 pest. He says that it is necessary to apply it early and to get the 

 material down to the roots. In 1908 Washburn 8 reports another 

 test which is similar to his above-mentioned report, in that the 

 checks were better than the treated plants. Collinge 8 of England 



2 Mich. Bd. Agr. Rpt. 1886, p. XXXIX. 



3 Can. Exptl. Farms Rept. for 1887, p. 22. 



4 Central Exptl. Farm (Can.) Bui. 11, pp. 14 and 29. 1891. 

 Can. Exptl. Farms, Rpt. 1898, p. 195. 



U. S. Dept. Agr., Ent., Bui. 46, p. 85. 1904. 

 6 N. Y. Cornell Exp. Sta. Bui. 78, p. 529 and 553. 



6 Minn. Exp. Sta. Bui. 100, p. 11-12. 1906. 



7 N. J. Exp. Sta. Bui. 200, p. 22. 1907. 



8 Minn. Exp. Sta. Bui. 112, p. 201. 1908. 



9 Collinge, W. E. Letter Feb. 17, 1913. 



