38 THE CANADIAN ENTOMOLOGIST. 



CORRESPONDENCE. 



EXPERIMENTS WITH YEAST IN DESTROYING INSECTS. 



We are indebted to Dr. H. A. Hagen, of Cambridge, for the following 

 letter and the subsequent remarks on this interesting subject : 



Kingsworth, Ashford, Kent, Dec. 27, 1881. 

 Dear Sir, — 



I beg to thank you very much for your letter, dated Nov., 1880, 

 respecting the application of yeast for destroying insect pests. During the 

 past season I have endeavored to follow the instructions contained 

 therein, and as you express a wish to hear of my success or failure, I will 

 attempt to describe my experiments as clearly as possible. As soon as 

 Aphides became noticeable, I procured some German compressed yeast, 

 dissolved an ounce in a little warm water, added a little coarse sugar, and 

 set it to ferment. In about 24 hours I added sufficient water to make up 

 a gallon, and with this syringed a cherry tree attacked by black Aphides. 

 This was on the 16th of June. Four days later I found the tree almost 

 clear of living Aphides, though their dead bodies, or cast skins (I could 

 not ascertain which, although I asked the assistance of an entomological 

 friend) smothered many of the leaves. One remarkable point in this 

 experiment was that a small branch of the tree, loaded with Aphides, hung 

 over a window, and at the request of my wife, I abstained from syringing 

 it. Here the insects remained perfectly healthy, and afcer a few days were 

 seen to work down the tree and attack the young shoots that had been 

 washed clean. On June 29th I again dressed the tree, and this time 

 destroyed or drove away every Aphide. I may add that the larvae of 

 several Aphidivorous insects were present on the tree, and did not appear 

 greatly affected by the application. Encouraged by the apparent success 

 attending the application, I commenced operations, June 20, on a second 

 cherry tree. This, however, was heavily leafed, and I could not make so 

 much impression, but they evidently did not like the dressing, tor they 

 disappeared entirely soon after the second application. I also tried the 

 yeast for Aphides on Guelder Rose (Viburnum), Elder (Sambucus), Field 

 Bean, and some other plants ; also for Currant Grub, but could make no 

 decided mark anywhere. With respect to the Currant and Gooseberry 

 Grubs, the liquid ran from off their bodies clean, and I found it almost 

 impossible to saturate tliem. with it. If the syringing was persisted in, they 



