268 THE AMERICAN MONTHLY [Oct 
Disinfection Against Msoquitoes. 
M. J. ROSENAU, P. A. S. 
Until lately, mosquitoes and flies were looked upon 
merely as annoyances, but since it has been proved that 
they are able to transmit the infection of pestilential dis- 
eases, we must now regard them as dangerous vermin. 
When the matter is generally understood, it will be a 
greater reproach to the housewife to have mosquitoes 
and flies in the home than bed bugs, and it is the duty of 
sanitarians to spread an abhorence for these most com- 
mon and most dangerous of domestic pests. The mosquito 
is known to transmit the infection of malaria and filari- 
asis. That the mosquito transmits yellow fever must now 
be accepted as an established fact. The next problem is 
the destruction of the infected mosquitoes. 
It is a well-known fact that formaldehyd gas readily 
enters into combination with the protoplasm of the lower 
forms of vegetable life, which makes it a very efficient 
germicide. It is, however, not toxic to the higher forms 
of animal life. It is very irritating in its effect upon the 
mucous membranes of rats, mice, guinea pigs, rabbits, 
and mammalian animals generally, but not necessarily 
fatal, even after prolonged exposures. Many insects, 
such as roaches and the like, may be exposed to strong 
concentrations of the gas a long time without effect. 
Formaldehyd gas kills mosquitoes whenever the gas 
comes in direct contact with them in sufficient concentra- 
tion and for a sufficient length of time. When exposed 
directly to the gas produced by any of the methods com- 
monly used for disinfecting purposes, the mosquitoes die 
within a few minutes. If the insects are confined in a 
bell jar and some formalin is dropped inside, they soon 
show signs of agitation and shortly drop down, dead. 
They may, however, live over night in a very feeble at- 
mosphere of the gas. 
