8 FARMERS ' BULLETIN 909. 



taken to clean premises and not returned to the quarters previously 

 occupied unless such quarters in the meantime have been cleaned and 

 disinfected or held vacant for about 20 days. 



The long-nosed sucking lice and the biting lice are much more 

 easily eradicated than the short-nosed sucking lice. One treatment 

 with arsenical dip or coal-tar creosote dip usually is sufficient to 

 eradicate the former, but as a rule one treatment does not eradicate 

 the short-nosed sucking lice. In fact, two treatments sometimes 

 fail to eradicate the last-named species, especially in the case of 

 infested bulls. When a herd is infested with all three species the 

 animals should be given two treatments separated by an interval of 

 15 to 16 days. After the second treatment the cattle should be 

 examined at frequent intervals, and if live lice are found a third 

 treatment should be given in about 16 days following the second. 



METHODS OF TREATMENT. 



There are three commonly used methods of applying treatment 

 for lice: First, hand applications; second, spraying; third, dipping. 

 The best method to adopt naturally depends upon the season of the 

 year, the remedies selected, the number of cattle to be treated, and 

 the facilities available. In southern latitudes, where the winters are 

 mild, cattle may be dipped during the winter months without injury 

 from cold weather; but in the northern sections the weather during 

 the winter season is usually too cold for dipping or spraying. As 

 hand applications are practicable only when a few animals are to be 

 treated, it is important that herds in which lice appeared during 

 the winter be dipped the following spring or fall. Fall dipping is 

 good insurance against both the risk of loss from lice and the prob- 

 able additional expense of winter treatment. All animals in the 

 herd should be treated regardless of the number showing infestation. 

 If only part of the herd is treated, or if after the second treatment 

 the animals are returned to infested premises, the parasites may 

 spread by contact of one animal with another, or by contact with 

 infested premises, and the herd almost certainly will become re- 

 infested. 



HAND APPLICATIONS. 



Dusting powders. The insecticidal value of many of the dusting 

 powders is dependent upon their naphthalene and pyrethrum con- 

 tent, and they are of value in helping to hold in check the parasites 

 during the season when the weather is too cold for dipping or spray- 

 ing. They are sold under various trade names, but as a class they 

 are not recommended as successful remedies for eradicating cattle 

 lice. 



