9 
different times, in the spring by preference, upon the manure of farms 
and stables and so on. 
Practical experimentation with this proposed remedy will be under- 
taken the coming spring in France. 
NATURAL ENEMIES. 
The house fly has a number of natural enemies. The common 
house centipede (fig. 9) destroys it in considerable numbers, there is a 
small reddish mite which frequentiy covers its body and gradually 
destroys it, it is subject to the attacks of hymenopterous parasites in its 
larval condition, and it is destroyed by predatory beetles at the same 
time. 
The most effective enemy, however, is a fungous disease known as 
Empusina musce, which carries off flies in large numbers, particularly 
toward the close of the season. The epidemic ceases in December, 
and although many thousands are killed by it, the remarkable rapidity 
A) 
C44 \" w= 
Be WAS . — 
Fig. 9.—Scutigera forceps: Adult, natural size (after Marlatt). 
of development in the early summer months soon more than replaces 
the thousands thus destroyed. 
WHAT CITIES AND TOWNS CAN DO. 
It would appear, from what we know of the life history of the common 
house fly and from what remedial experimentation has already been car- 
ried on, that it is perfectly feasible for cities and towns to so greatly 
reduce the numbers of these annoying and dangerous insects as to ren- 
der them of comparatively slight account. The health departments of 
most of our cities have the authority to abate nuisances dangerous to 
health, and it is easy for the health authorities of any city to formulate 
rules concerning the construction and care of stables and the keeping 
and disposal of manure which, if enforced, will do away with the house- 
fly nuisance. Such a series of rules was formulated in the spring of 
1906 by the Health Department of the city of Asheville, N. C., and an 
effort is being made during this summer to see that they are enforced. 
On the 3d of May, 1906, the Health Department of the District of 
Columbia also issued a series of orders of this nature, on the authority 
