﻿THE CATTLE GEUBS OR OX WARBLES 105 



the grub aperture often retards healing. This may contain the 

 exuviae of the larvse, but usually it seems to be composed of dried 

 excretions from the cyst. As the opening heals about this tough 

 material there often remains a pit containing a minute hole which 

 can be located with a pointed instrument. 



Observations have been carried on to determine the rapidity of 

 healing of grub holes in the skin when the grubs are killed by the 

 application of insecticides or are extracted by hand. It has been 

 observed that where grubs are squeezed out, or even drop normally, 

 the old cyst and other material left within it require several weeks 

 for absorption. Grubs were extracted on one side of the backs of 

 cattle and on the corresponding side they were killed with insecti- 

 cides. Two weeks later these animals were slaughtered and ex- 

 amined. The condition of the connective tissue around the grub 

 cysts was practically identical on both sides. When the skin was 

 removed no discolored or infiltrated tissue was left on the carcass, 

 but the former position of the grubs could be located on the under 

 side of the hide. The holes in the hide had healed to about the same 

 degree with the exception of a few cases in which portions of the 

 bodies of the dead larvae were in the grub openings, thus preventing 

 the closing of the apertures. 



In several herds in which insecticides were administered to the 

 backs of the cattle, a number of subsequent examinations were made 

 to determine the general condition of the infested areas and the 

 rapidity with which the skin healed. In most of these herds the 

 grubs were not treated until many of them were nearly mature. 

 Seventy-seven days following the treatment it was found that be- 

 tween 42 and 62 per cent of the grub holes had healed, and the fact 

 that the animals had been infested with larvae could not then be 

 determined by touch. One hundred and twelve days following 

 treatment 75 per cent of the grub holes were completely healed and 

 smooth. At this time only 2 per cent remained open and in no case 

 was more than a very slight quantity of pus present. In one herd 

 treated with benzol it was found that the healing was less ad- 

 vanced at the end of 77 days. Only 30 per cent of the grub holes 

 were healed and smooth, and 48 per cent of the holes were still open. 

 The presence of the grubs was apparent in 25 per cent of the cysts. 

 In all cases, however, the warbles were distinctly reduced in size. 



Since in certain animals extraction is greatly facilitated by 

 puncturing the grubs and squeezing out their contents before re- 

 moving the grub skin, the writers have treated over 200 head in this 

 way. In no instance did the condition of the lesions and the rapidity 

 of the healing of the holes in the skin show any difference from 

 those in cases in which the grubs were extracted by squeezing. In 

 a number of cattle the grubs were punctured and left in the cyst 

 after the body contents had been |)ressed out. No ill effects were 

 observed, but healing of some oi th(! lioles in the skin was retarded, 

 owing to the hardening in thcin of tlie skins of the grubs. One ani- 

 mal treated in this way had GO well-develo))e(] grubs in its back. 

 Six days after the puncturing, about 10 of the grubs were project- 

 ing from the skin. These were shrunken and hardened, and seven 

 of these were pulled out. There was no more pus in any of the 

 cysts than would occur with living larvie. Twelve days later six 



