TESTS WITH INSECTICIDES UPON GAEDEN INSECTS. 



By William B. Alwood, Special Agent. 



LETTER OF TRANSMITTAL. 



Columbus, Ohio, October 30, 1886. 

 Sir : I inclose herewith a summary of my tests with different insecticides. These 

 are not written in the style of a report, but to acquaint you with the results I have 

 obtained. My work is just begun, and I do not feel as though anything creditable 

 in the way of a report could be furnished so far. I trust this will be satisfactory 

 and furnish you with what information you desire concerning the progress of the 

 work thus far. If you desire it I can furnish a copy of the original notes from 

 which this summary is made up ; however, many of my serial tests were noted in bulk 

 instead of keeping an individual record of each test. This was done because of same- 

 ness and lack of importance in the individual record. This matter would have 

 reached you a week sooner had I not been ill for several days. I will forward some 

 notes about machinery in a few days. 



Very respectfullv, 



WM. B. ALWOOD 

 Prof. C. Y. Eiley, 



U. S. Entomologist. 



KEROSENE EMULSION. 



Formula. — Kerosene, 67 per cent.; water, 33 per cent.; whale-oil 

 soap sufficient to form a stable emulsion. 



This preparation was used on several insects with somewhat varying 

 results, the chief features of which are condensed in this note. 



On Cabbage Worms. 



The first series was begun before Plusia brassier was numerous, hence 

 only Pieris rapw is spoken of. The emulsion was used in different di- 

 lutions, ranging from equal parts of water and emulsion to 16 parts of 

 water and 1 of emulsion. It was in all cases applied as a spray, and 

 when the worms were numerous and eating vigorously. Several hun- 

 dred plants were used in the field tests. Weaker solutions than 1 of 

 emulsion to 3 of water were of no avail unless applied very heavily, and 

 then they caused considerable injury to leaves. In the proportion of 1 

 to 3 it was quite effective where the worms could be reached, i. e., were 

 not under the leaves, and destroyed about 75 per cent, of them. It did 

 not injure the leaves in this strength if properly sprayed. Where so- 

 lution of 1 to 5 was put on excessively it killed and also injured plants. 

 Stronger solutions than 1 to 3 were not more efficacious and injured 

 plants seriously. The weaker solutions would sicken the worms and 



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