38 BULLETIN" 597, IT. S. DEPARTMENT OF AGRICULTURE. 



Some of the tsenicides and larvicides which have been successfully 

 used upon insects, as well as soapy enemas, were tested upon detached 

 larvae in tin boxes. As with other Gastrophilus larvae, remarkable 

 resistance was noted. It will be observed that negative results were 

 obtained by using the common tsenicides, 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 larvae 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 man} T 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 

 larvae pass as a result of the treatment, and some remark upon the 

 beneficial effects of the removal of larvae 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 larvae 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 i-dram capsules hold about 3 drams of carbon disulphid. 



Desiring to know the periods of time required to kill the larva? in 

 the treatments, a number of experiments have been conducted in 

 fumigating stomach sections to which larva? were attached. Only 

 larvae from those animals that could be secured shortly after the death 

 of the hosts were used, and the sections with larva? in situ were placed 

 in wooden boxes tightly covered with glass after the box was well 



