38 BULLETIN 597, U. S. DEPARTMENT OF AGRICULTURE, 
Some of the tenicides and larvicides which have been successfully 
used upon insects, as well as soapy enemas, were tested upon detached 
larvee in tin boxes. As with other Gastrophilus larve, remarkable 
resistance was noted. It will be observed that negative results were 
obtained by using the common tenicides, that soap solutions seemed 
more effective, and that nicotine sulphate gave good results. 
LARVAL TREATMENTS. 
Experimenters have been impressed with the resistance of Gastro- 
philus larve to various contact substances, and it is practically 
agreed that any contact substance capable of killing the larva would 
seriously injure the stomach membranes of the horse. The internal 
method for use must necessarily be in the form of a fumigant. The 
use of carbon disulphid internally, as brought out by Perroncito and 
Bosso, has been tried and indorsed by many veterinarians. A list of 
indorsements from many countries can be found in articles dealing 
with this subject. Originally the disulphid was administered in 
12-gram capsules surrounded by aloes, the whole contained in 48- 
gram gelatine capsules. In the hands of various workers it has been 
subjected to modifications, but each reports that large numbers of 
larvee pass as a result of the treatment, and some remark upon the 
beneficial effects of the removal of larvee upon the animal. 
The Bureau of Animal Industry, after employing this treatment 
upon a number of horses, recommends the following procedure: 
The day preceding the treatment a small amount of hay and a moderate 
amount of oats is given in the morning; in the evening food is withheld and a 
purgative given—Barbados aloes 1 ounce, or raw linseed oil 1 pint. The day of 
the treatment, at 6 o’clock in the morning, give 3 drams of carbon disulphid in 
a gelatin capsule; at 7 o’clock repeat the dose in the same manner; and at 
8 o’clock give the third and last dose, making in all 9 drams of carbon disulphid 
in three gelatin capsules. 
The above treatment is for the adult horse. For a yearling colt half the 
quantity of carbon disulphid used for a mature horse will give the desired 
results. If properly administered the gelatin capsule reaches the stomach 
intact, but soon dissolves and the carbon disulphid rapidly evaporates, suffo- 
cating all bot larvee and other parasites with which it comes in contact, but 
not injuring the horse. Worms are quite often expelled as well. 
The Bureau of Animal Industry calls attention to the fact that 
the so-called 4-dram capsules hold about 3 drams of carbon disulphid. 
Desiring to know the periods of time required to kill the larve in 
the treatments, a number of experiments have been conducted in 
fumigating stomach sections to which larve were attached. Only 
larvee from those animals that could be secured shortly after the death 
of the hosts were used, and the sections with larvee in situ were placed 
in wooden boxes tightly covered with glass after the box was well 
