186 THE HOUSE FLY—DISEASE CARRIER 
Some one else in England and possibly some one 
else in France seem to have discovered the same fact 
in very much the same way. According to Galli- 
Valerio (1910), a ten-per-cent, formalin solution has 
been recommended by certain European writers. Tril- 
lat and Legendre, for example, advised ten-per-cent, 
formalin solution with the addition of twenty per cent, 
milk. The Fly Committee of the Merchants’ Associa¬ 
tion of New York, on the basis of an item in the Lon¬ 
don Lancet, have advised the use of formaldehyd. A 
number of correspondents, however, have written that 
they found it unavailing. Dr. Daniel S. Hager, of 
Chicago, for example, used formaldehyd in water and 
also formaldehyd in milk; a few flies were found about 
the receptacle, but the results as compared with the 
results of fly paper were insignificant. 
Hodge (1911) states that he has been successful 
in the use of a teaspoonful of formalin to a teacupful 
of water. He fills a big bottle with the mixture, in¬ 
verts it in a saucer and mounts the whole in a most 
likely place. Sweetening it or mixing it with milk or 
other foods to make it more attractive will, he says, 
result in the destruction of flies. 
Herms, of the University of California (1910), 
states that formaldehyd has given thorough satisfaction 
as a substitute for poisons. He points out that it is 
non-poisonous to man, and may therefore be used with 
impunity around food. It is a powerful germicide and 
does not injure delicate fabrics. He states that forma¬ 
lin as purchased in the drug store is in about forty-per- 
