10 CIRCULAR 148, U. S. DEPARTMENT OF AGRICULTURE 
stomach worm, because of the tumors which they produce. The 
tumors interfere to a considerable extent with the proper functioning 
of the stomach. When large tumors are situated near the junction 
of the stomach and intestine they interfere mechanically with the 
passage of food. The most evident injury occasioned by the large 
stomach worms is produced by the larve which get into the skin of 
horses where they are commonly associated with a skin disease known 
as Summer sores. 
Treatment.—A high degree of efficacy for the destruction of Z. 
muscae and H. microstoma has been obtained by the use of the fol- 
lowing method of treatment. The animal should be fasted for from 
18 to 24 hours and the stomach washed out by injecting through a 
stomach tube 8 to 10 quarts of a 2 per cent solution of sodium bicar- 
bonate (baking soda) heated to 105° F. The solution tends to remove 
the thick layer of tenacious mucus which normally covers the lining 
of the stomach and renders the stomach worms more accessible 
to the action of drugs. It is advisable, though not necessary, to 
siphon off the sodium bicarbonate solution. If the solution is not 
siphoned off, an interval of 15 to 20 minutes should elapse before 
further treatment. Carbon disulphide should then be administered 
in capsule or by stomach tube in a dose of 6 fluid drams (24 cubic 
centimeters) for a 1,000-pound animal, or at a dose rate of 1.5 fluid 
drams (6 cubic centimeters) for each 250 pounds of weight. No 
purgative should be used with this treatment. H. megastoma in 
stomach tumors is not affected by this treatment and is inaccessible 
to any method of treatment known at present. 
Prevention.—Prevention of stomach-worm infestation in horses 
involves the storage of manure in closed containers, in order to de- 
crease the number of flies which breed in manure, or the application 
of other control measures designed to prevent flies from breeding. 
The use of containers for storing manure with a view to destroying 
egos and larve of parasites is discussed subsequently in this circular. 
The United States Bureau of Entomology has devised a trap de- 
signed to destroy fly maggots which breed in manure. ‘The trap is 
based on the observation that maggots, when fully grown, migrate 
out of moist manure and if they are permitted to escape through 
spaces between the boards of an open manure platform raised on 
posts and set in a concrete basin of water, they are caught in the 
basin and drowned. This and various other methods of controlling 
the house fly and stable fly are given in Farmers’ Bulletins Nos. 1408 
and 1097. 
SUMMER SORES 
A skin disease of horses, known as summer sores and characterized 
by pronounced skin lesions, is associated in some parts of the world, 
including the United States, with the larve of the large stomach 
worms of horses. The sores may be as small as a millet seed, but 
are usually about the size of a pea and may attain a size about an 
inch in diameter. The sores are covered by a soft, brownish-red, 
pulpy material with cracks or furrows which are filled with pus. 
In the midst of the softened mass there are small, rounded granu- 
lations which are firm in texture, 
