PARASITISM 127 



used frequently, is safe and helpful if done with reasonable cau- 

 tion. Volatile substances, especially wood alcohol, are effective, 

 dry rapidly, are moderate in cost, and are safe in cold weather, 

 when reasonably used. They are more effective, also, than a 

 powder. Powdered sodium fiuorid is effective for biting lice but 

 not for sucking lice. 



For poultry use whitewash in abundance, and plenty of fine, 

 air-slaked lime dusted into the nests and on the floor. It is a 

 good plan to throw this lime against the wall, so that it will 

 float in the air and then gradually settle down into crevices and 

 over the poultry. Or kerosene may be sprayed over the walls 

 and ceiling and the perches frequently washed with it. Kero- 

 sene is cheap, can be rapidly applied, and is very effective. 

 Constant access to dust bath of dust or sifted ashes, air-slaked 

 lime, sulphur, and Persian insect powder, should be given and 

 the poultry house should be kept dry. 



Flies. — At times flies prove a serious nuisance for domestic 

 animals, particularly horses and cattle. Various preparations 

 have been tried at different experiment stations with fairly sat- 

 isfactory results. 



No. 1. — Was tested and reported as satisfactory by the 

 Nebraska Experiment Station: Oil of wood tar 1 part; neutral 

 oil (a petroleum product) 4 parts. Mix and shake thoroughly. 

 A very light application of this should be made by brush or 

 spray. It is occasionally necessary to sponge off the hair with 

 a cloth, using a little of the neutral oil on account of a little gum 

 which collects with repeated application. 



The following (Jensen) is probably still better: Dissolve 1 

 pound naphthaline in about 1% gallons crude oil, applying just 

 sufficient heat to effect solution. Add to this 1 gallon of fish oil. 

 In a separate vessel, dissolve about 2y 2 pounds of common laun- 

 dry soap in about 5 gallons of water. When the soap solution 

 is complete, mix it with the oils and naphthaline, put it 

 into an old churn and work it thoroughly together, adding 

 gradually sufficient water to make the product measure 10 gal- 

 lons. Apply daily or twice a week as needed with brush or 



spray. 



Sheep tick (Melophagus ovinus).— This is not a true tick but 

 a wingless fly. The young larvae are attached at birth to the 

 wool fibers. The pupa stage last from three to six weeks, after 

 which maturity is reached. It is a permanent parasite, i.e. the 



