32 CIRCULAR 148, U. S. DEPARTMENT OF AGRICULTURE 
Such a procedure is too wasteful for farm practice, as the manure 
must be utilized and is safe after it has been stored for a time. 
Conditions of storage should permit the spontaneous heating process, 
which is destructive to eggs and larve of parasitic worms, to act 
throughout the manure for a sufficient time. 
When manure is stored in open piles it heats in the middle but 
remains cold on the surface. Such manure is dangerous, so far as 
parasite transmission is concerned, because the eggs and larve pres- 
ent on the surface of the manure pile escape destruction. It is, 
therefore, important that the outer 3 or 4 inches of exposed manure 
piles be turned over every week or so in order to bury the exposed 
manure under the inner material of the pile and sterilize it by 
heating. If this is not done, the manure should not be placed on 
any field to which horses may have access even months later, as the 
eggs and larve of many species of parasites are longlived and very 
resistant to unfavorable influences. It has been determined that the 
eggs and larve of parasites present In manure can be more certainly 
and easily destroyed if the manure is stored in closed containers - 
or boxes, having double walls and a double floor, with a 4 to 6 inch 
space between the walls and floor filled with sawdust, and the top 
of the container covered with a well-fitting lid. (Fig. 23.) It is 
essential that the containers be tight in order to retain as much heat 
as possible; the greater the heat developed and retained in manure 
boxes the sooner the eggs and larve will be destroyed. 
The sawdust acts as an insulator, but even with this precaution 
it is desirable to use tongue-and-groove lumber in the construction 
of manure containers in order to make them tight. Concrete boxes 
will not serve, as the manure at the sides is chilled and there is not 
heating enough to destroy parasites. 
For practical purposes manure which has been kept in such con- 
tainers for at least two weeks may be considered free from lving 
egos and larve of parasites and may be safely spread on pastures. 
Several manure boxes constructed on the above principles have been 
in operation at the Beltsville station of the Bureau of Animal In- 
dustry with successful results. These boxes have double-walled doors 
to facilitate the removal of the manure after it has been sterilized. 
In default of such measures, spread horse manure on fields which 
are to be pastured by animals other than horses, or plow it under. 
SUMMARY OF CONTROL MEASURES 
The most common and most troublesome parasites of horses in 
the United States live, at least part of their lives, in the digestive 
tract, either free in the lumen, attached to the walls, or embedded 
in the lining of the wall. These parasites produce eggs which pass 
out in the manure on to pastures, the floors of stalls, and other 
places. All such worm infestations in horses trace back to manure 
as the original source. 
Manure must be regarded as dangerous, and control measures 
should be designed to prevent contaminating the feed and water 
with manure so far as it is possible to do so. The following meas- 
ures are designed to reduce the possibilities of gross infestations of 
horses with parasites: 
