524 DISEASES OF CATTX,E. 



Treatment for warhles. — In the late winter and spring examine 

 the cattle for the presence of warbles. Bj' passing the hand over the 

 backs of the animals the swellings marking the location of the grubs 

 may be readily found. Pressure properly applied to the swellings 

 will cause the grubs to " pop out " if they have reached a late stage 

 of development. They may be more easily removed by means of 

 slender forceps inserted into the opening of the warbles, and a still 

 more certain method of removing them is to cut into the swellings 

 with a sharp knife or bistoury, after which they may be pressed out 

 through the opening thus made. Care should be taken to crush all 

 grubs removed, so as to prevent the possibility of their further de- 

 velopment and transformation into flies. In order that none of the 

 gi-ubs may escape it is advisable to examine the cattle every two 

 weeks during the late winter and spring, at each examination remov- 

 ing the grubs which liave developed suflficiently to cause perceptible 

 swellings. 



Another method of treatment is to force grease or oil into the open- 

 ings of the warbles, which kills the grubs. This method is less cer- 

 tain than that of removing the grubs, and has the further objection 

 that the dead grubs remain beneath the skin. Claims have been ad- 

 vanced that the use of arsenical dips, as employed in tick eradication 

 (see p. 504), has reduced the number of grubs in the cattle which have 

 undergone treatment, but it is uncertain whether these claims have 

 a solid foundation in fact. Cattle may be treated during the sum- 

 mer with fly repellents (p. 518) to keep off warble flies. The efficacy 

 of repellents against these flies is probably, however, not very great. 



In localities where the character of the cattle industry is such as 

 to render practicable the systematic examination of cattle and the 

 removal of the grubs — that is, where the herds are comparatively 

 small and subject to the close supervision of the owners — it is pos- 

 sible, by the exercise of a little care and with very little effort on the 

 part of the cattle owners, provided they work together, each doing 

 his share by seeing to the removal of grubs from his own cattle, so 

 that as few as possible survive to transform into flies, to reduce the 

 number of grubs within one or two seasons almost, if not entirely, 

 to the point of extinction. It still remains to be determined whether 

 a practicable means of eradication, by arsenical dips or otherwise, 

 can be devised for use in the case of herds which can not readily be 

 treated by direct removal of the grubs. 



LICE.^ 



Three species of lice, two of them sucking lice {Hcematopinus eury- 

 sternus^ the short-nosed cattle louse, and H. vihiU, the long-nosed 

 cattle louse), commonly known as blue lice, and one biting louse 

 {Trichodectes scalaris), commonly known as red louse, affect cattle. 



* For further information see Bulletin 5, new series, Bureau of Entomology. 



