158 MOSQUITOES OF NORTH AMERICA 
“The fungus also was found at the same time on several specimens of Mus- 
cide, on a Chironomid, and on Diplaz, probably D. rubicundala. Attempts were 
made to introduce the disease into new regions, but with little success. In the 
laboratory, a large piece of bark bearing mosquitoes killed by the disease was 
placed in a cage with many mosquito larve and pup. A few adults died after 
emerging but not nearly all of them. 
“ On August 7, a number of pieces of bark covered with mosquitoes killed by 
the fungus, were placed on the margins of a pool in the river woods. The dis- 
ease had not previously appeared in that section. On August 13 a few dead 
mosquitoes were found near the place where the infection was made. On August 
23, the disease was widespread throughout these woods.” 
Marchoux, Salimbeni and Simond found that in Brazil the yellow-fever mos- 
quito (Aédes calopus) was the bearer of several fungi. These fungi they found 
to be very abundant at certain seasons of the year. These parasites not only 
invade the digestive tract but also the body-cavity, in that case causing the mos- 
quito’s death. 
Perroncito found a bacterial parasite in Anopheles in Italy. This parasite 
proved pathogenic, in fact it was the mortality it caused among mosquitoes that 
led to its discovery. The parasite infests the larve and finally destroys the mos- 
quito soon after it has transformed to adult. 
Dyé, in 1904, in an excellent summary on the parasites of mosquitoes, dis- 
cussed the yeasts found in mosquitoes as follows: 
“We ought to give some words to the yeasts found by several authors in 
mosquitoes. 
“In October, 1900, Laveran announced a case of an yeast parasitic on Culi- 
cide. This author has observed, in sections of Anopheles maculipennis, the ex- 
istence of an yeast in the coelomic cavity of mosquitoes coming from Rio-Tinto 
(Spain) ; they had sucked malarial blood and had been well preserved in abso- 
lute alcohol. According to Laveran this yeast presented the appearance of 
minute ovate elements, measuring from 2 to 5 » in length; a certain number of 
these cells had at one extremity a small bud; each one of them possessed a 
nucleus which was readily stained by the process of Heidenhain. 
“ The greater part of the yeast cells are free in the coelomic cavity, or they are 
grouped in small masses. In a number of longitudinal sections of these 
Anopheles Laveran saw clearly that this yeast passes through the epithelium of 
the walls of the digestive tube and falls into the ccelomic cavity. 
“This yeast appears to be pathogenic for the mosquito; in fact, following the 
observations of Laveran, Dr. Macdonald of Rio-Tinto investigated systematically 
these small cell-elements which he succeeded in finding again. He noted, more- 
over, that the larvee of Anopheles die rapidly at the season of the year at which 
one finds the Anopheles infested by the yeast described by Laveran. Hence it 
is probable that the yeast is transmitted from the larva to the adult insect, as in 
the case of the parasitic fungi of Culicide observed by Perroncito. 
“ Marchoux, Salimbeni and Simond also have observed yeasts in most of the 
Stegomyia calopus which they had occasion to examine in the course of their in- 
vestigations'on yellow fever. They found them particularly in mosquitoes dis- 
sected soon after their emergence: they exist in abundance, especially in the 
ceelom of the mosquitoes, in individuals fed with honey, with fruits and with 
sweet substances. These authors note that these yeasts differ according to the 
character of the food of the insect. 
