PREVENTIVE MEASURES 
187 
cent, solution and should be diluted with water down 
to five per cent, or eight per cent.; in other words, add 
five to six times as much water. This solution, he 
says, should be sweetened with sugar or made attractive 
by adding milk. 
He advises partly filling a shallow vessel, such as an 
individual butter dish, and placing it upon the table 
or in the show window. He states that the flies drink 
this material and die not far from the containers. In 
the dining-room where there is water, milk, or other 
liquid food, flies are said not to be so greatly at¬ 
tracted to the formalin, but where this is made the 
only source of drink for the insects the results are 
said to be remarkable. Herms recommends that all 
other liquids except the formaldehyd dishes in a 
given room should be removed or securely covered 
in the evening, so that the flies have only the formal¬ 
dehyd to drink early in the morning when they begin 
to fly. 
Some careful experiments were tried during early 
February, 1911, at New Orleans, La., at the request 
of the writer, by Mr. T. C. Barber. Mr. Barber’s notes 
indicate success. The mixture used was formaldehyd 
( forty-five per cent.), two ounces; sugar, two ounces; 
water, ten ounces. On February 14th he placed some 
of this solution in an open saucer in the show window 
of a grocery store, where a few flies were present. 
After being left about one hour, seven dead flies were 
found in the window, which had previously been thor¬ 
oughly cleaned. He then placed the material in two 
