CATTLE LICE AND HOW TO ERADICATE THEM. 11 



One dipping sometimes eradicates the lice, but it can not be de- 

 pended upon in practical operations, especially when the animals 

 are infested with the short-nosed sucking lice. The first dipping 

 if properly done may kill all the lice or cause them to leave the 

 animals, but it may not destroy all the eggs. Some of the eggs often 

 survive the first dipping and hatch, thus forming a new generation 

 of lice. To complete the treatment this new generation should be 

 destroyed by a second dipping before they have had time to de- 

 velop to maturity and deposit eggs. On the other hand, the second 

 dipping should be delayed long enough to give the eggs which were 

 laid before the first dipping sufficient time to hatch; otherwise they 

 may hatch after the second dipping and reinfest the cattle. Because 

 of overlapping of the two periods and of variations in the incubation 

 period and the period required for lice to reach maturity it does not 

 seem possible to meet both of these conditions in establishing the 

 length of the interval between dippings, but a period of 15 to 16 

 days has generally given satisfactory results. 



When conditions are such that an infested herd can not be dipped 

 twice, one dipping in arsenical solution or coal-tar creosote dip will 

 amply repay the cost and effort. If complete eradication is desired, 

 however, two dippings should be given with an interval of 15 to 16 

 days between dippings, and sometimes a third dipping may be nec- 

 essary. 



DIRECTIONS FOR DIPPING. 



If dipping is to be successful it is necessary to give close attention 

 to details and see that the work is performed carefully and thor- 

 oughly. Before bringing cattle to the vat they should be watered 

 and fed so as not to be hungry or thirsty at the time of dipping; 

 on the other hand, they should not be gorged with feed and water 

 when dipped. If they are watered and fed two to four hours before 

 dipping, they are likely to be in the best condition for the operation. 

 When cattle have been driven and are hot at the time of reaching the 

 vat. they should be allowed to cool off before they are dipped, as 

 it is dangerous to dip animals while they are hot. When the nights 

 are cold dipping should be finished for the day early enough for 

 the animals to become dry before sunset. 



The dip in the vat should be maintained during dipping at a depth 

 of 70 to 80 inches, or sufficient to swim the iallest animal to be dipped. 

 The quantity of dip necessary to obtain that depth should be ascer- 

 tained before it is prepared. The average 1,000-pound short-haired 

 steer will carry out and retain about 2 quarts of dip, and the same 

 class of cattle with long hair will retain about 1 gallon each. The 

 total estimated amount of dip which the animals carry out and retain, 



