58 THE HOUSE FLY—DISEASE CARRIER 
the spray must be thinly applied. The best result 
reached by this method was ten days. The reverse, 
namely, spraying with alcohol and shellac and then 
dusting with rice powder, was satisfactory where the 
shellac was not applied too thickly. Colored chalks 
gave very satisfactory results, yellow and brick red 
being the best; the yellow lasting for nine days and the 
brick red for twenty days. 
Length of Life of the Adult 
It seems that in midsummer the adult flies do not 
live long, and it is extremely difficult to keep them 
for any length of time in an enclosure, which, of course, 
is the only true way of ascertaining exact age. At this 
time of the year, flies die rapidly in confinement. In 
June, 1898, the writer was unable to keep alive flies 
collected at large and placed under a gauze enclosure 
three feet cube for more than three days, but of course 
this experiment meant nothing, since the age of the 
flies collected was not known. Mr. Hine is convinced 
that flies do not live a great many days in warm sum¬ 
mer weather. Marked flies in his experiments in Au¬ 
gust were not to be found after the third day, and in 
his experiments with individuals, in confinement with 
all necessary food, he was unable to keep them alive for 
more than twelve days. He mentions an instance where 
on a farm at Ira, Ohio, a pile of infested manure at 
the barn was hauled up and spread in a field a quarter 
of a mile away on August 15th; the occupants of the 
house stated that there was a notable reduction in the 
