218 



A description is given of the various stages of the larva, which is 

 specially adapted to attach itself firmly to the mucous membranes 

 of the host. The imagines of R. purpureus occur during the whole 

 summer. They do not feed during their short life and are active only 

 during the warm part of the day, the females being especially so when 

 sexually mature. 



For the control of this fly, the author advises making use of its 

 habit of resting on elevated objects in the fields, such as fences, stones, 

 etc., among excreta of birds, which they much resemble, where they 

 can be easily caught by hand. By putting up trap fences in pastures 

 and collecting the insects from the woodwork every day, preferably 

 in the morning, large numbers can be destroyed. Trap boards must 

 face with one side south and one side must be protected from the 

 prevalent winds. The same remedy can also be utilised against 

 Cephalomyia maculata, Wied., in districts where camels are kept. 



Cooper (W. F.) & Laws (H. E.). Some Observations on the Theory 

 and Practice of Dipping. — Parasitology, Lo7idon, viii, no. 2, 

 September 1915, pp. 190-217, 2 figs., 1 plate. 



This paper contains an account of investigations carried out at 

 EUiotdale, British East Africa, on the process of dipping as a means of 

 tick eradication. A brief description of the dipping bath is given. 

 The process of dipping is very rapid and economical ; from 400 to 600 

 head of stock can be dipped in an hour at a cost of ?; to |- of a penny per 

 head. The concentration of the fluid should vary according to the 

 interval between each successive dipping and the species of tick to be . 

 killed. South African ticks may be divided into three classes in this 

 respect, of which Margaropus {Boopliilus) decoloratus (blue tick) forms 

 one; Ambh/o^nma hebroeum (bont tick) and Hydomma aegyptium 

 (bon't-legged tick), a second ; and Rhipicephalus appendiculatus 

 (brown tick), the third. A. hebmeum, which is important as a trans- 

 mitter of heartwater, is most difiicidt to kifl ; the dipping -fluid must 

 be moderately strong and an interval of two weeks between the dippings 

 is sufficient. The life-cycle of R. apjyendiculatus is so short that dipping 

 must be repeated at frequent intervals. An interval of three days was 

 adopted ; this was subsequently lengthened to five days, since it was 

 found that the stock remains distasteful for at least two days after 

 dipping. The addition of an emulsion to sodium arsenite solution 

 allows the concentration of the solution to be considerably reduced 

 without decreasing the effectiveness of the wash, and at the same time 

 the stock can be used continually for work and ploughing. • A separate 

 bath should be used for sheep. Instead of making the cattle swim 

 through a bath, they may be driven through a tunnel into which the 

 dipping-fluid is sprayed by means of suitably arranged jets. The 

 spray bath, although condemned as being less thorough in its effects, 

 has been successfully used at EUiotdale in all the investigations. The 

 use of a too concentrated fluid gives rise to the so-called " scalded " 

 condition. 



Conflicting views are held as to whether the tick absorbs the poison 

 through its skin or imbibes it with the blood which it sucks from its 

 host. Experiments tend to prove that the second view is the more 

 correct one. The fact that engorged females are rendered infertile 



