206 SANITARY ENTOMOLOGY 



eggs and get rid of larvae. Clipping of the hair oh the legs has also 

 been recommended but is not entirely satisfactory. Dove has experi- 

 mented with certain halter devices for the protection of horses in pas- 

 tures and also with various types of guards to be used on horses in 

 harness to prevent the attack of the nose fly (fig. 40). In the first case 

 he used a halter, from whi(^i is suspended a box-like arrangement tliat 

 covers the nose when the horse has its head up, but permits of grazing 

 and drinking. A canvass extends back under the jaw to prevent deposi- 

 tion of eggs by the throat bot, and of course the covering of the mouth 

 prevents the ingestion of eggs of the common bot. The main difficulty 

 has been the production of a durable device of this kind. The nose fly 

 attack is best prevented by a rectangular piece of belting being suspended 

 from the bit rings immediately below the lips, when horses are at work. 



The internal treatment of infested animals with carbon disulphide 

 has been found to be very effective if properly done. Three three-dram 

 doses at hourly intervals are given in capsules succeeding a period of 

 starvation and followed by a purgative. 



Pre: ention of Attack in Man. — The reduction of the number of hots 

 by treatment of the lower animals will greatly reduce the chances of in- 

 festation in man. Care should be taken not to ingest eggs or larva; 

 when infested horses are being clipped or groomed. 



Prevention of Attack by Other Forms. — This group includes 

 those species accidentally infesting man such as the ]Muscids Mnsca 

 domestica, and Muscina spp., Fannia, and Syrphus flies. 



Destruction of Breeding Places. — Since most of these forms are 

 breeders in excrementitious matter and decaying vegetation, the proper 

 care of manure of all kinds is important. This has been discussed in other 

 lectures. Since some of the species, especially Fannia, breed in accumu- 

 hitions of decaying vegetation such as straw, roots, etc., these should 

 receive attention, especially when close to camps. 



Destruction of Flies. — The use of traps is eff*ective against most 

 of the species concerned except the small Phorids and Syrphids whicli are 

 not inclined to enter traps baited with usual baits. Poison baits and 

 fly paper will also destroy some species other than the house fly. 



Food and Water. — The careful preparation of uncooked food such 

 as cress, lettuce, etc., is important. No doubt many of the cases of infes- 

 tation by Fannia and Eristalis have been due to the eating of improperly 

 washed foods of this kind. Drinking promiscuously from streams and 

 pools should not be permitted. During the Great War the provision of a 

 good water supply for the men received first consideration. Of course 

 this is im})ortant to prevent infestation with various disease organisms. 

 Distillation, filtration and chlorination are the preferred methods of 



