22 Farmers' Bulletin 801. 



has been very limited. Prior to the work of the writers its only known 

 insecticidal use was against cockroaches, for which it has been 

 demonstrated to be very effective. Owing to this limited demand 

 the material is not ordinarily found in drug stores. Druggists, 

 however, can obtain it readily from manufacturmg chemists in the 

 larger centers, and with demand it will be carried in stock by many 

 local dealers. The commercial sodium fluorid at present prices 

 should be retailed at from 30 to 60 cents per pound, the price varying 

 somewhat with the amount ordered by the druggist and the distance 

 from the chemical manufacturing centers. 



Sodium fluorid in a dry state does not deteriorate quickly. It 

 should be kept in a dry place either in bottles with stoppers or 

 in closely covered cans. In this condition it will remain active 

 indefinitely. 



METHODS OF APPLICATION. 



In treating poultry with sodium fluorid, if proper methods are 

 followed, a remarTcahle degree of control is ohtained. One applica- 

 tion of sodium jluorid to all fowls on given premises will completely 

 destroy all lice present.^ It is essential to make sure that the treat- 

 ment is thorough and that every fowl is treated, for if one infested 

 chicken escapes it will m a short time reinfest the entire flock and thus 

 make it necessary to do the work over at a considerable loss of time 

 and money. 



Sodium fluorid may be applied in two forms, as a dust and as a 

 dip. In using either form the first step is to see that all fowls are 

 shut in the poultry house or placed in coops prior to beginning 

 treatment. 



DUSTIXG. 



The action of sodium fluorid when applied in dust form is com- 

 paratively slow; hence, if fowls are examined the day following treat- 

 ment, or even two or three days later, some lice may be found. The 

 material persists, however, and after four or five days all lice disap- 

 pear. Apparently the hatching of the eggs is not prevented, but the 

 young lice find sufficient material present in the feathers upon 

 emerging from the eggs to destroy all of them. 



For complete destruction of lice it is essential that small amounts of 

 the material be placed on different parts of the infested birds. Con- 

 trary to the usual belief, all species of fice do not migrate freely 

 from one part of the bird to another, hence the material must be 

 well distributed to brmg it in contact with all lice present. 



The writers have found what they term the ''pinch method" to be 

 entirely effective against all lice and to have the advantage of 

 economy of time and material. Wlien the material is applied by this 

 method (see illustration on title-page) it is placed on a table in an 

 open vessel, and the fowl is held by the legs or wings with one hand, 

 while with the other hand a small pinch of the chemical is placed 



> As an example of complete eradication, a flock of 150 Wyandottes treated by the owners at Raymond-, 

 111., in November, 1917, was found to be absolutely free of lice in April, 1919. 



