1880.] Destruction of Obnoxious Insects by Fungoid Growths. 6 33 
some cases the cotton plants upon which the worms were feeding 
were thoroughly drenched with active yeast. In one instance 
a number of the larve were placed in a tin box and drenched for 
twenty-four hours with yeast; after this the surplus yeast was 
drained off and the larve kept in the same box and fed fora 
week without showing any symptoms of disease. They were 
then sent to the department at Washington, where they arrived 
safely, and never gave those receiving them cause to suppose that 
they had been thus treated. Similar results attended all the 
experiments tried by Mr. Trelease, and he was led to the conclu- 
sion that the proposed remedy could not be utilized for the 
destruction of the cotton caterpillar. 
On the other hand, Dr. Hagen mentions some experiments made 
last summer by Mr. J. H. Burns, of Shelter Island, N. Y., on the 
potato beetle, as being successful. A quantity of beetles was 
divided into two parcels, one of which was sprinkled on succes- 
sive days with dilute yeast. 
On the eighth day those sprinkled began to die, and on the 
thirteenth all were dead. Of the unsprinkled parcel only a few 
had died. That this experiment is decisive can hardly be claimed, 
as it is probable that some other substance, as for instance, dilute 
flour paste, which would favor the growth of fungi, might have 
had the same effect as the yeast. At all events, the experiment 
Must necessarily be tried upon the beetles as they are found in 
their natural state infesting the potato plants, before any definite 
conclusion can be drawn. 
It is true that Dr. Hagen found spores in quantity in the large 
Sinus of the wing of.the dead beetles which had been sprinkled, 
but it does not appear that these were in any way directly con- 
nected with the Torule of the yeast. It should also be noted that 
Dr. Hagen states in the May number of the Canadian Entomolo- 
gist, for 1880, that he has recently received a letter from Germany, 
giving an account of the use of the diluted (compressed) yeast 
upon aphides in a green-house, “ which was successful to an ex- 
ceeding degree ;” but no details in regard to the experiment are 
given. 
Possibly the kind of yeast used may make a great difference in 
the result, although it should be remembered that three different 
kinds have been used in the experiments detailed in this paper. 
It is also worthy of note that yeast, as suggested by Prof. 
VOL. Xiv NO, IX 41 
