632 Destruction of Obnoxious Insects by Fungoid Growths. [Septr, 
Experiment No. 8.—This experiment is introduced as a test of 
o. 
May 11.—Two aphides are taken from a plant which has been 
treated with yeast. One is dead when found, the other is killed; 
both are placed as in No. 7. No mycelium or fungoid growth of 
any kind is developed in this experiment. 
Experiment No. 9.—This experiment was introduced for the 
same purpose as No. 8. 
May 11.—5.30 P.M. Three living aphides are taken from a 
plant not treated with yeast, and killed and placed as in No. 7. 
May 13.—The room has been quite cool and no mycelium has 
appeared, 
May 15.—On one of the aphides a few fruits of a mold can be 
discerned. None can be seen on the other two. 
This experiment seems to show that the mold developed in 
experiment No. 7 on the body of the aphis which had died, has 
no connection with the fact that the plant from which the dead 
aphis was taken, had been treated with yeast. 
The result of these experiments, as a whole, as also many 
others not here recorded which have a more or less direct bear- 
ing upon the subject under consideration, indicate plainly that 
yeast cannot be regarded as a reliable remedy against such insects 
as commonly affect plants cultivated in greenhouses, rooms and 
parlors. Moreover, it is more than probable that the yeast would 
injure many kinds of plants, especially those with delicate foliage 
by spotting and soiling the leaves, and inducing fungoid growths 
upon the jars or soil in which the plants are grown. - Indeed, in 
most greenhouses at the present time, it is not so much a ques- 
tion of keeping down injurious insects, as it is the suppression of 
molds and mildews of various kinds. The verbena rust only 
need be named as an illustration of this point. sa 
Nearly all recorded experiments with the yeast fungus as an 
insecticide, have been attended only by negative results. Among 
these may be mentioned those of Prof. J, H, Comstock, of the 
Department of Agriculture, who fed caterpillars in breeding . 
cages with leaves wet with dilute yeast. They seemed to thrive 
as well as others not thus fed. : 
Mr. Wm. Trelease tried last August a number of experiments 
with yeast upon the cotton-worm, in the vicinity of Selma, Ala. 
These experiments were varied and carefully conducted. In 
r “ Report upon Cotton Insects.” J. H. Comstock, Dept. of Agr. Washington, 
1979. 7 
i 
