176 THE HOUSE FLY—DISEASE CARRIER 
best, and it would also undoubtedly be the best in any 
event if, by co-operation of the residents or by the 
active efforts of a central body, like the boards of health 
in cities, it were possible to do thorough work with the 
breeding places. 
In cities and in towns, however, where the requisite 
co-operation cannot be obtained, and where boards of 
health are still indifferent, careful consideration must 
be given to the second method, namely, keeping flies 
out or killing them after they enter. 
A third method has been proposed and is enthusi¬ 
astically advocated by Professor Hodge, of Clark Uni¬ 
versity, Worcester, which is based upon the supposed 
time elapsing between the issuance of the adult fly and 
the period when it lays its first eggs. Professor Hodge, 
as will be shown later, thinks that it is quite possible 
to trap these sexually immature adults during this 
period, which now seems comparatively long, and thus 
to prevent not only their entrance into houses and shops 
and markets, but to destroy so many of them that the 
comparatively few which reach sexual maturity will 
not be able to lay their eggs in sufficient numbers to 
make the next generation a nuisance. In other words, 
he thinks that it will be possible to bring about such a 
condition that the manure pile may be left undisturbed 
until it is needed to fertilize the land. 
Whether this can be done or not—and Professor 
Hodge’s argument seems reasonable—will again de¬ 
pend upon co-operation in communities, although indi¬ 
vidual effort in isolated places may bring it about. 
