WINTER NUMBER 39 
above, these records do not begin to show the loss of efficiency 
among the students, which is much higher than is shown by these 
bare records. 
Yellow Fever 
We have only to turn the pages of history to see how fatal an 
epidemic of yellow fever may be. In 1773, Philadelphia was 
nearly wiped from the map. In 1853 there was a severe epidemic 
throughout the South, New Orleans alone having a mortality of 
eight thousand. In 1878 another severe epidemic swept this 
region, and spread up the Mississippi Valley, causing twelve 
thousand deaths. In 1892 there were one hundred and ninety- 
two deaths at Pensacola, and more recently there was an out- 
break, in 1905, in which nearly one thousand lives were lost. It 
was clearly demonstrated by Reed, Carroll, Lazear and Agro- 
monte, a Board appointed by the Surgeon-General of the United 
States Army to investigate this disease, that yellow fever is car- 
ried by a mosquito, Stegomyia calopus. The work done in the 
recent epidemic, in 1905, shows that an epidemic can be stamped 
out by destroying these mosquitoes. 
We have Stegomyia present in large enough numbers to cause 
trouble should an epidemic break out. I have killed as many as 
a half dozen in the laboratory in one afternoon, and for a while 
during the fall of 1911 they were very troublesome during the 
day at the Experiment Station. At present, there is no danger 
from them because we have no causal agent present to start an 
epidemic, but it may be introduced into Florida ports at any 
time, and this will be especially true with the increased trade 
incident to the opening of the Panama Canal. 
Dengue fever is another mosquito-borne disease that is of in- 
creasing importance. Dr. J. H. Hodges, local agent of the State 
Board of Health, estimates that there were five thousand cases 
in this county alone last year. While this estimate is probably too 
high, it shows that this disease must be reckoned with in the 
future. 
NATURAL ENEMIES OF MOSQUITOES 
Some adult mosquitoes are destroyed by birds, bats, dragon- 
flies, and other predacious insects, but their number is compara- 
tively small. 
A small mite determined by Dr. Nathan Banks as a Hydrach- 
nid, close to the genue Thyas, has been found parasitic on the 
body of Anopheles. During October and November, it was found 
attached to from ten to fifteen per cent of the Anopheles caught, 
