xxxvill DEPARTMENT REPORTS. 



EXPERIMENTS IN ZOOLOGICAL DEPARTMENT, 1886. 



Much time was spent early in the season to determine the value of several 

 insecticides; the effect upon plants as well as upon insects was closely watched. 

 The results of these investigations are herewith presented. 



KEROSENE EMULSION. 



Previous experiments having showed that a milk emulsion is no better than 

 a soap emulsion, and is often harmful to foliage, a soap emulsion was the 

 only one used. 



One lb. of Whale Oil soap was mixed with a gallon of water and all heated 

 to the boiling point, when a half gallon of kerosene was added and thor- 

 oughly stirred while yet boiling. In several cases common soft soap was used, 

 when the quantity of soap was doubled. 



Applied to Radish Maggot (Anthomyia raphani, Harr.) 



'The emulsion was diluted with water till the kerosene formed one-tenth of the 

 volume of the liquid used. The first application was made when the plants had 

 been up one week and were one inch high. It was repeated once in three or four 

 days for four weeks. The application was made upon each plant singly, a table 

 spoonful being used each time. That we might be certain that each plant was 

 treated the application was made with a glass tube with a rubber nipjjle attach- 

 ment. For simply practical use the liquid could be turned on from a common 

 watering pot, when more would be used. This would not injure the plants. At 

 the expiration of the four weeks, twenty-four consecutive plants upon a treated 

 row were pulled and carefully examined. Only six plants were injured at all by 

 the maggots. An adjoining row containing thirty-two plants was also exam- 

 ined and twenty-two of these plants were injured. 



The soil was loose sand, and the plants were not at all injured by the appli- 

 cation. 



Applied to the Cherry Slug {Selandria eerasi, Peck.) 



The emulsion one to eighteen strong was applied to several infested trees. 

 The slugs were annoyed but not killed. The following day most of them seemed 

 as well as ever. Some of the small ones were killed. The foliage was not 

 injured. 



The application was made by use of Woodason's bellows atomizer. 



Applied to Cabbage Caterpillar {Pieris rapce, Schrank.) 



No experiments were tried in the field. Upon larvae feeding in the labora- 

 tory the emulsion was used one to twelve strong. In every case the insects 

 were killed. They all died in less than three hours. Similar experiments 

 with a liquid one to twenty strong, seemed to do no injury to the caterpillars. 



Applied to Rose Slug {Selandria rosce, Harr.) 



The emulsion one to twelve strong was applied by use of a cyclone nozzle 

 and Whitmore's fountain pump. The application was very successful in 

 destroying the slugs and did no harm to the plants. 



