304 A TICK-RESISTANT CONDITION IN CATTLE. 



specimens forwarded by him regularly to Dr. Porter, Cam- 

 bridge Universit3% laid eggs from which larvse hatched but 

 lived only for a day (R.8.C., p. 12), investigation failing to 

 reveal the cause of such widespread destruction. 



Pound (1914, p. 110) stated that ticks picked up natur- 

 ally by Clover and Tinkerbell as well as those applied artific- 

 iall}', eventually laid eggs which hatched normally, the 

 progeny being in no way impaired. In his report for 1915- 

 1916 (1916, p. 90) practically the same information is given. 

 One of us found that there was little difference (if any) 

 in regard to the laying and hatching of eggs of ticks taken 

 irom a resistant cow and from a ticky control animal (R.S.C., 

 p. 59). In some cases no hatchings were obtained, but these 

 were due to climatic or other conditions — chiefly drying. 



Fertility tests were carried out at Eumundi with 

 ticks obtained from November, 1917, to February, 1918. 

 These ticks, 55 of which were from the following eleven 

 resistant animals. Dot, Donkey, Fairy, Jockey, Kittiwake, 

 Peewee, Rosie, Rainbow, Squib, Sunset and Yellow; and 42 

 from seven non-resistant animals (mostly calves) were placed 

 in loosely stoppered tubes and kept in a fairly cool, moist 

 place on the easterly side of the house. These observations 

 were concluded in Brisbane in February and March. The 

 results were : — 



Ticks from (a) resistant. (b) ncMi-resistant animals 



Normal fertility (i.e., 



ticks of whose eggs 



80 % or over hatched) 54 % (approx.) . . 78 % (approx.) 



Partial fertility {i.e., 



under 80 %— 



usually about 60 %) 42 % (approx.) . . 17 % (approx.) 



No hatching . . . . 3 % (approx.) . . 4 % (approx.) 



Tests carried out by Mr. Hull during 1917 afforded very 

 different figures. He supplied us with full details of these 

 tests. His results were based on observations of 113 ticks 

 removed from 11 resistant animals and 138 ticks removed 

 from 10 ticky animals during the period February-November, 



1917. 



Ticks from (a) resistant. (5) non-resistant animals. 



Normal fertility 4% (approx.) .. 19% (approx.) 



Partial fertility 13 % (approx.) . . 38 % (approx.) 



No hatching . . . . 83 % (approx.) . . 42 % (approx.) 



These ticks were kept in match boxes and in a rather 

 hotter and drier part of the house than that used by us. 



