ENTOMOPHTHORA 157 
FUNGI AND BACTERIA. 
Thaxter has recorded attacks on adult mosquitoes by the fungus known as 
Entomophthora spherosperma. It reaches Diptera generally, but is especially 
noticeable with the mosquitoes. Another fungus (EZ mpusa culicis) also destroys 
mosquitoes in both Europe and America. Thaxter also states that Empusa 
papillata destroys small gnats (probably mosquitoes among them). The eggs of 
Psorophora howardu were found in the summer of 1901 to be covered with a 
fungous growth which has been determined by Mrs. F. W. Patterson, of the U. 
8. Department of Agriculture, to belong to the genus Polyscytalum. 
A most interesting instance of the destruction of mosquitoes by Entomoph- 
thora is described by Mr. R. H. Pettit in Special Bulletin No. 17 of the Michigan 
Agricultural Experiment Station (see pl. VII, fig. 2). 
“On August 5, Mr. Barlow found a number of adult mosquitoes killed by a 
fungus, Hntomophthora sp. nov. They were very numerous on the margins of 
one of the pools in the north woods, sometimes almost covering the soil and the 
pieces of bark to which they clung. Some were just killed and showed little, if 
any, external growth, and some were covered with a dense dull white growth. 
All were within a few inches of the water and all faced away from it. Imagine 
thousands of mosquitoes all headed away from the water as if they were trying 
to get away from it. 
“Tt would seem that the effect of the disease is to draw the affected insects 
to the water, possibly by creating a thirst, after slaking which the insects, in 
trying to retreat, are caught and stopped in their course by numerous rhizoids 
or anchor ropes which are sent out by the fungus in the body to fasten the victim 
permanently to the place where its ill luck overtakes it. Unfortunately for the 
mosquito host, the diseased individuals die just in the right place to infect their 
fellows as they go to the pool to drink or to lay eggs. This is a case where the 
fungus seems to influence the host in such a way as to lead to the spread of the 
disease. Similar impulses seem to be induced in the case of other species—the 
Sporotrichum that is used against chinch-bugs seems to impel the diseased in- 
dividuals to hide under clods or in other moist and protected places, just the 
places where the young bugs come to shed their skins or to molt. This is of 
course the best possible way to spread the disease. Then, too, in the case of the 
common grasshopper disease, Zmpusa grylli, the dying hoppers are impelled to 
climb to the tops of weeds and plants, and as the fungus throws its spores to some 
distance, there is a good chance that some of them will fall on the bodies of other 
grasshoppers. 
“The appearance of the mosquito fungus is quite characteristic. The entire 
body is swollen and covered with a dull white growth, sometimes almost 
plumbeus. The body is fastened down by many slender brownish ropes. A 
microscopic examination shows the growth to be made up of fine threads 
(mycelium) bearing spores at their distal extremities. These threads are 
usually simple, though sometimes bearing a few short branches. They are 
septate at long intervals, granular, and contain vacuoles. The spores are lunate, 
bluntly rounded at both ends. In size they measure about 50 microns long by 
13 in diameter, some being as long as 55 microns and a few as short as 28 
microns. They are finely granular, with oil globules usually near the ends. In 
a single specimen large numbers of resting spores were found. In this case the 
mycelium had largely disappeared. The resting spores were spherical, hyaline, 
with many small translucent interior globules. They measured from 40 to 44 
microns in diameter. 
