158 MOSQUITOES OF NORTH AMERICA 



" The fungus also was found at the same time on several specimens of Mus- 

 eidae, on a Chironomid, and on Diplax, probably D. ruhicundala. 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 larvge and pupae. 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 (Aedes cdlopus) 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 larvge and finally destroys the mos- 

 quito soon after it has transformed to adult. 



Dye, 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- 

 cidse. This author has observed, in sections of Anopheles maculipennis, the ex- 

 istence of an yeast in the coelomic cavity of mosquitoes coming from Eio-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 ju, 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 coelomic cavity. 



" This yeast appears to be pathogenic for the mosquito ; in fact, following the 

 observations of Laveran, Dr. Macdonald of Eio-Tinto investigated systematically 

 these small cell-elements which he succeeded in finding again. He noted, more- 

 over, that the larvas 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 Culicidaj observed by Perroncito. 



" Marchoux, Salimbeni and Simond also have observed yeasts in most of the 

 Stcgomyia 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 

 ccelom 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. 



