THE CANADIAN ENTOMOLOGIST. 39 



would release their hold and fall to the ground, but very shortly crawl up 

 again. To conclude, I was delighted with the apparent success of my 

 first experiment, but all subsequent trials were so discouraging that I fear 

 yeast is too uncertain in its action to supersede many of the washes we 

 have already in use. Again thanking you for your kind letter, I beg to 

 subscribe myself, sir, Yours most respectfully, 



Thos. H. Hart. 

 To Dr. H. A. Hagen, Cambridge, Mass., U. S. A. 



This interesting letter by Mr. Thos. H. Hart, who owns nurseries and 

 greenhouses, allows the following conclusions : 



I. It is doubtless true that in the experiments of June i6 and 20, the 

 Aphides were killed, as upon the branch not syringed they remained in 

 perfect health. 



II. It is doubtless true that the later experiments were a failure. 



III. It seems evident that the yeast has not contained Isaria, or.other 

 fungi obnoxious to insects, to which the first success could be ascribed ; 

 otherwise the later application of the same fluid ought to have had the 

 same effect, or even by the multiplication of the fungi, a more marked 

 effect. 



Experiments made in Germany and here had exactly the same result, 

 first success, later failure. In Germany it was made on a jasmine, in a 

 flower pot, and the previously rather sick plant was in 1881 in good health 

 and perfectly free of Aphides. Some currant shrubs on the left side of 

 my house were entirely free through the whole year (without fall gener- 

 ation) after the experiment, though similar shrubs on the right side of my 

 house were badly infested with currant worms ; I had here purposely not 

 applied yeast. After all I believe it can be concluded that a certain stage 

 of the yeast solution is needed to make it effective, and that after this 

 stage it becoines indifferent. That yeast solution has killed insects seems 

 to be undoubtedly proved, and it remains only to find out the stage in 

 which its application is successful. It is sure that success, even in a very 

 small number of experiments, cannot be annihilated by failure in other 

 experiments. H. A. Hagen. 



pieris rap.^ in nebraska. 

 Dear Sir,— 



I am sorry to note the appearance of P. rapes in Nebraska. August 

 3rd, 1 88 1, I first saw a living specimen ; needless to add that it was busily 



