﻿106 BULLETIlsr 1369, U. S. DEPAETMENT OF AGEICULTUEE 



projecting grubs were pulled out; tlie cysts under these were small 

 and the animal had improved noticeably in condition of flesh. At 

 this time more than one-half of the holes were healed. When the 

 grubs are punctured before they are extracted the cattle are wor- 

 ried much less than when extraction by the usual method is prac- 

 ticed. Schottler (87) states that in Germany a crochet needle has 

 been used for puncturing and extracting grubs, but that this method 

 had been found to be undesirable because the juice from the grubs 

 may cause nettle fever. 



COST OF TREATMENT OR EXTRACTION OF GRUBS 



To gain information on the expense of treating cattle for grubs, 

 records were kept on the time required in applying the different 

 treatments, the quantity of the material used, and its cost. 



It was found that for cattle of the island breeds hand extraction 

 was the most economical. The time consumed in extraction varied 

 considerably with the breed and with the local conditions under 

 which the work was done, as well as with the experience of the 

 operator. The rate of extraction per hour ranged from 38 grubs 

 in Holsteins to 191 in a dairy herd of mixed breeds. It appears 

 that with the average herd of Jerseys or mixed breeds, not Holsteins, 

 the grubs can be extracted carefully and thoroughly at the rate of 

 about 125 per hour. Naturally the degree of infestation affects the 

 rate, as in very light infestations much time is occupied in going 

 from one animal to another and in very heavy infestations more 

 care is necessary to avoid missing some grubs. 



In tests in which the backs of the cattle were thoroughly moistened 

 with soap solution the average number of larvae extracted per hour 

 was 119, and where normal salt solution was applied prior to 

 the extraction the grubs were removed at the rate of 100 per hour. 

 These tests therefore seem to indicate that the whetting of the backs 

 of the cattle in the case of island or mixed breeds, not Holsteins, 

 tends to retard the rate of extraction. 



In tests of the method of extracting the grubs after puncturing 

 them and expelling the contents, the average number of grubs re- 

 moved per hour was slightly over 88. This work was done without 

 special forceps, which if used would have hastened the work. Al- 

 though this rate of extraction is considerably sl'ower than that of 

 the hand extraction in Jersey or mixed herds it is decidedly more 

 rapid than hand extraction" in Holsteins, 



The rate of treatment when injecting the cysts with a hypodermic 

 syringe ran about 170 grubs per hour. The time consumed in in- 

 jecting the material by means of an oil can varied considerably, 

 ranging from 74 to 240 grubs per hour. The very slow record 

 mentioned was probably due to the fact that a large number of 

 the grubs had dropped, and it was necessary to examine each cyst 

 to determine if the larva was still present. Under good conditions 

 in a dairy it is thought that by the oil-can injection method 225 

 grubs per hour might be readily treated. 



The application of such general treatments as dusts and washes 

 is considerably more rapid than the individual treatment of grubs. 

 The thoroughness with which either of these methods must be car- 

 ried out, however, causes more time to be consumed in the treat- 



