600 Cun Pine 
neither do they hover over the water surface and dance in the air. Rapi 
streams are unfavorable to them, and they shun even slow-running eurrents 
Because of the ripples at the shore, not a single fly was found in the lake 
regardless of the proximity of the pools and overflowed areas. 
Factors affecting the adult 
Absence of salt in water 
Unlike the larva, the adult does not require salt; it lives on the surfac 
of salt water, but it lives on fresh water also. In the laboratory, adult 
were often confined on the surface of fresh water immediately followin 
their emergence. Food was provided, and the flies lived, in most cases 
from six to twelve days. 
Heat 
A newly emerged adult subjected to a temperature of 36° C. in th 
greenhouse died within three hours. A second one, kept in the sam 
confinement but at a temperature between 25° and 26° C., lived until th 
next afternoon, when the temperature suddenly rose to 34°. The condition 
here were, however, different from those outdoors. There was no shad 
for the fly to seek and no current of air, and the fly itself was deprived o 
liberty in changing from one place to another. Therefore in the field 
temperature of 35° might not have affected it fatally. 
Rainfall 
Excess rainfall is beneficial to the adults in that it widens the water 
surface of the overflowed areas, maintains the normal salinity in the pools, 
and eliminates the chance for the loss of the natural habitat. 
From the data gathered during the months of June, July, and August, 
in the two years 1916 and 1917, it was seen that the number of flies 
materially increased during the periods of greater rainfall. 
Frost and snow 
Unless frost is extremely heavy, it has very little effect on the adult 
flies. In September, when the frost was light there was not much change 
in the number of flies in the field; but later, when conditions were different, 
the following records were obtained: 3 
November 1. Considerable frost; no dead flies found. 
