102 • 



Hence the prolonged infectivity of Atiopheles does not appear to be 

 possible. Compared with the trypanosome salivary infectivity of 

 Glossina, which is generally lasting, continuing until the death of 

 the infected fly, the plasmodial salivary infectivity of Anopheles is only 

 temporary and fleeting. Therefore the salivary medium in mosquitos 

 cannot be regarded as a hibernating medium for malarial sporozoits. 



Thomson (F.), Keogh (F.) & Tucker (G.). Eradication of the Cattle 

 Ticli. Observations on the Efliracy of the Tick-destroying Mixtures 

 approved by the Queensland Stock Department, according to the 

 Method and the Thoroughness of their A.pplication.--Qi(eenslcmd 

 Agric. Jl., Brisbane, viii, no. 6, December 1917, pp. 302-307. 

 [Received 1st March 1918.] 



The Queensland cattle tick, Margaropus {Rhipicephalus) annulatus 

 australis, is a one-host tick, spending the whole of its parasitic life of 

 21 days on one animal. Owing to the minute size of the larval forms 

 there is a great danger of a slight infestation being overlooked in its 

 early stages, and since one female deposits from 1,500-3,000 eggs, a 

 thorough treatment of tick-infested cattle is of the first importance. 



Highly successful results have been obtained for many years by 

 dipping in a solution of 8 lb. arsenic in 400 gals, water containing 

 dissolved soap, but as there has been a tendency of late years to 

 reduce the amount of arsenic and to substitute spraying for dipping, 

 experimental work has been undertaken to show the necessity for the 

 most careful preparation of dipping fluids in accordance with the 

 Government formula. 



A dip prepared according to the Department's formula of : — 

 Commercial arsenic 8^ lb., caustic soda 4 lb., tallow 4 lb., Stockholm 

 tar \ gal., water 400 gals., gave highly satisfactory results on cattle 

 dipped every 14 days. 



A dipping- vat, which at working level held 2,800 gals., was charged 

 as follows : — 2,000 gals, of water were run into the vat ; 59| lb. com- 

 mercial arsenic was mixed with 14 lb. caustic soda in the dry state 

 and placed in a 400-gal. tank with about 20 gals, water, the mixture 

 being stirred for a few minutes till the ingredients boiled and the 

 arsenic dissolved. Cold water was then added till the tank was full, 

 when the mixture was well stirred and run into the dip. Next, 

 50 gals, water were run into the tank and heated to boiling point ; 

 14 lb. caustic soda and 28 lb. tallow were then added and boiled to- 

 gether for I hour. Cold water was then gradually added, heating 

 being continued, but the mixture was kept below boiling point, ^^^len 

 the tank was half full, 3| gals. Stockholm tar were added, and the mix- 

 ture was well stirred. Heating was continued and water gradually 

 added till the tank was full, when the mixture was thoroughly stirred 

 and run into the dip. 



It was found that there is a striking difference in the efficacy of a tick- 

 destroying fluid according as it is used for dipping or spraying. The 

 latter is so unreliable that its use for treating tick-infested or suspected 

 cattle before travelling into clean country should not be countenanced 

 when a suitable dip is available. If it is unavoidable, the cattle 

 should be sprayed as often as necessary and held in a clean place 

 till they are proved by the most careful inspection by an experienced 

 person to be thoroughly clean. 



