1880.| Destruction of Obnoxious Insects by Fungoid Growths. 581 
means of a flat paint brush so that all parts, especially those cov- 
ered with aphides, are fairly wet. The yeast used is fresh domes- 
tic yeast, diluted with two-thirds water. Torulz are active, as is 
shown from the fermentation in progress. After being sprinkled 
the plant is placed by itself on a table and covered by a large 
funnel-shaped hood, made of thin white paper, slightly open at 
the bottom to admit air. A cup of actively fermenting yeast is 
placed at the side of the plant under the hood, so that any germs 
which may possibly escape from the yeast will be confined to the 
air immediately surrounding the plant. Some of the older leaves 
are infested with a number of scale insects. 
May 15.—No dead aphides are to be found. Some cast-off 
skins from molting are seen. 
May 18—Peduncles and tips of runners are loaded with plump 
aphides. Many cast-off skins. No dead insects are found. The 
scale insects larger and apparently more numerous. 
May 20.—All young parts completely covered with aphides. 
June 3.—The plant is obviously injured from attack of aphides 
and scale insect. Some of the leaves are dead. The plant is out 
of flower and the peduncles are more or less withered. On these 
peduncles are a number of dead aphides. These might have 
Starved for want of food, owing to the drying up of the juices of 
the peduncles. A number of dead aphides are examined under 
the microscope in a variety of ways, but in no case is there any 
appearance of Torulz or other fungoid growths. Numerous live 
aphides are found on the younger parts of the plant. 
- Experiment No, 2—May 13—A small geranium plant (Pe/ar- 
gonium angulosune var.), infested with a considerable number of 
aphides, is sprinkled with domestic yeast (the same as in No. 1), 
and placed in a window in its ordinary position among other 
plants not infested. 
May 15:—Aphides more scattered but apginti not Tas in 
number. 
May 18.—Aphides plainly more numerous, Numbers of cast- 
off skins. from molting. Some leaves of geranium with dark- 
brown spots obviously caused by drops of yeast; other plants of 
‘the same kind not treated with yeast show no spots. 
June 3. —Aphides numerous and healthy. Quantities of cast- 
off skins. No dead aphides to be found, Foliage obviously 
injured by the yeast. Plant plainly enfeebled by the aphides. 
À [Zo be S 
