328 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



has been used to a limited degree, by forcible attenuation in water and 

 spray, while some plants withstand doses of the pure oil. But the safe 

 and general use of kerosene for the purpose under consideration, dates 

 from the year 1880. Of the various substances used in attempts to 

 emulsify and mix kerosene with water, none are more satisfactory than 

 soap and milk, both being everywhere accessible and cheap. Milk was 

 first suggested in 1880, by Dr. YV. S. Barnard, while carrying on ex- 

 periments for me against the Cotton-worm, and subsequent experiment, 

 especially by another of my assistants. Mr. H. G. Hubbard, has given 

 us the simplest and most satisfactory method of making the emulsion 

 quickly and permanently. An emulsion resembling butter can be pro- 

 duced in a few minutes by churning with a force pump two parts of 

 kerosene and one part of sour milk in a pail. The liquids should be at 

 about blood heat. This emulsion may be diluted with twelve or more 

 parts of water to one part of emulsion, thoroughly mixed, and may be 

 applied with the force pump, a spray nozzle, or with a strong garden 

 syringe. The strength of the dilution must vary according to the 

 nature of the insect to be dealt with, as well as to the nature of the 

 plant; but, riuely sprayed in twelve parts of the water to one of the 

 emulsion, it will kill .most insects without injury to the plant. An 

 equally good emulsion may be made as follows: 



Kerosene, 2 gallons; common soap, one-half pound; water, 1 gallon. 



Heat the mixture of soap and water and add it boiling hot to 

 the kerosene. Churn the mixture by means of a force pump and 

 spray nozzle for five or ten minutes. The emulsion, if perfect, forms a 

 cream, which thickens on cooling, and adheres without oiliness to the 

 surface of glass. Dilute with cold water before using, to the extent 

 which experience will indicate is best. 



The simplest discoveries are often the most valuable, and this dis- 

 covery of so simple and available a means of diluting, ad libitum, oil 

 with water is important and far-reaching in its practical application. 

 It were foolish to detain you with details of the several directions in 

 which it has proved of great benefit, and which are recorded in my 

 recent writings, especially in the reports of the entomologist of the 

 Department of Agriculture for 1881-82 and 1883, and in Bulletins 1 

 and 2 of the Entomological Divi>iou of that Department. 



Pyrethrum roseum, a plant native to the Asiatic countries south of the 

 Caucasus Mountains, and Pyrethrum cineraricefolium, a native of Dal- 

 matio, have long been known to possess insecticide properties, especi- 

 ally in the powder from the dried and pulverized flowers. The powder, 

 sold under various names by druggists, was chiefly used against house- 

 hold pests, however, and though Mr. 0. Willemot, as early as 1857, in 

 France, and Mr. William Saunders, in 1879, in Canada, tried it in powder 

 form on some that are injurious to plants, its importance as a field in- 

 secticide did not appear till in 1880, when, in prosecuting the work of 

 the United States Entomological Commission, we discovered that it 

 could be used in liquid solution. During the winter of 1880 and 1881, 

 1 succeeded in importing a hu ge quantity of the seed of both species, 

 and on behalf of the above named commission, distributed it to a num- 

 ber of correspondents in various parts of the country with a view of 

 establishing its cultivation. Since then large quantities have been dis- 

 tributed from the Department of Agriculture. Both species proved to 

 be hardy throughout the greater portion of our country, and Mr. G. X. 

 Milco, of Stockton, CaL, has, for some years, cultivated dneraricefoliwm 

 quite extensively at great profit, the product being sold under the name 

 of "Buhaek." The insecticide property dwells in a volatile oil. It acts 



