278 STATE HORTICULTURAL SOCIETY. 



mixed at all times, and may be kept in stock in a dilute or concentrated 

 form for any period. Here again the match test shows that there is no 

 free oil at the top. We have tried a very large number of cases, in all tem- 

 peratures the past winter, and have not had a single failure. Dr. Riley's 

 formula always fails in our hands, no matter how careful we are, to make a 

 perfect emulsion. We now have a large number of bottles of diluted emul- 

 sion, of both kinds, made at different times, and every one of the Riley 

 diluted emulsions can be distinguished at once by the free oil. In every 

 case, upon dilution, the Riley emulsion shows this free oil, not a lighter 

 emulsified liquid, at the top. The eye would detect it; its inflammable 

 character proves the eye right. Lay a paper on it, and as soon as the 

 paper is wet take it off and touch a lighted match to it, and it flames up 

 like a kerosene torch. I wondered if our kerosene oil — our Michigan law 

 requires an exceptionally high test — might not be the cause of this, and so 

 I sent to Ohio, Indiana, Illinois, and even Ames, Iowa, where Prof. Gil- 

 lette conducted his experiments, for the grstde of- oil used in those states. 

 These were carefully tried and all acted precisely alike. Not one gave us 

 a perfect emulsion with the Riley formula, as shown by the dilution, when 

 free oil rises at once to the top, while every one did give a perfect emul- 

 sion with mine. Prof. Gillette writes in a private letter: " I do not 

 believe it is practicable to make emulsions to be kept before diluting I 

 think they should always be made as wanted and diluted as soon as made." 

 We do not find this true at all of our emulsion; we find it just as good, just 

 as satisfactory, and very convenient to keep it in stock and dilute as we 

 wish to use it. We have found this very convenient not only in summer, 

 but also in winter, when we keep it in the barn ready to use for lice on the 

 stock. But we do find it true of the Riley emulsion, and even then imper- 

 fect emulsion makes the diluted liquid unsatisfactory. This fact makes my 

 formula, as we think, very decidedly superior to the Hubbard-Riley. We 

 should consider it a decided calamity had we to give up my emulsion and 

 use the other. The general farmer is not used to experimentation, and we 

 must make all such work as simple and easy as possible, or he will refuse 

 to use our remedies. It is barely possible that the hot climate of Florida, 

 where Mr. Hubbard conducted his experiments, might make a difference, 

 but as we have worked in warm rooms I do not think this can be true. 



The superiority, then, of the emulsion which I advise, rests in ease and 

 certainty of emulsion, ease of forming a dilution at any time which may 

 be kept indefinitely, and. most important, the fact of perfect emulsion. I 

 hope all station entomologists and horticulturists will thoroughly try both 

 these formulas that our farmers and fruitgrowers may be advised most 

 wisely the country over. This is the more desirable, as there is a widely 

 increasing place for the use of this very valuable insecticide. 



Prof. L. R. Taft has made the above experiments independently, and 

 states to me thAt he agrees with everything I have said in the above 

 discussion. 



kerosene emulsion for plant lice. 



I have never seen the small black plant lice eggs so abundant as at the 

 present time, April 1, 1891. I have never received so many inquiries 

 regarding them, nor received so many specimens from curious or anxious 

 farmers. Just about as the buds of the fruit trees, etc., commence to open 

 these eggs will hatch; and unless some natural enemy reduces their number — 



