149 



the proportion of 1 to 10. The present author found that 10 per cent, 

 of laurel oil in cottonseed oil was active for less than a day." 



" In experimental tests carried out by the present author the 

 following results were obtained : 



"A 10 per cent, mixture of crude carbolic acid (21-8 per cent. 

 phenols) in cottonseed oil has a very strong repellent action on flies, but 

 this lasts less than a day, in consequence of which it is necessary to 

 apply the mixture every day. The mixture should be applied lightly 

 with a brush, since a heavy application with a spray pump is likely to 

 cause phenol poisoning. 



" Mixtures consisting of 10, 20, and 50 per cent, of pine tar in cotton- 

 seed oil have marked repellent qualities. They should be applied 

 lightly, and it is necessary to apply them every day. A liberal applica- 

 tion of a 10. per cent, mixture is deleterious to animals. This is also 

 the case with a half-and-half mixture of pine tar and Beaumont oil 

 when applied lightly with a brush. 



" A mixture of oil of tar (14 per cent, phenols, volatile with steam) 

 in cottonseed oil and in Beaumont oil has a very marked repellent 

 action. A 10 per cent, mixture of oil of tar in cottonseed oil is safe. 

 A half-and-half mixture of oil of tar and cottonseed oil, when applied 

 liberally with a spray pump and 50 per cent, oil of tar in Beaumont oil 

 applied with a brush are not safe. Ten per cent, oil of tar in Beaumont 

 oil is safe. When applied lightly it is necessary to apply 10 per cent, 

 oil of tar in cottonseed oil or 10 per cent, oil of tar in Beaumont oil 

 every day. 



" Mixtures of 10 per cent, oil of citronella, oil of sassafras, or oil of 

 camphor in cottonseed oil are powerful repellents, but they are active 

 for less than a day. 



" A heavy application of fish oil causes the hair to become sticky and 

 fall out. A light application did not produce these results. 



" Pyrethrum powder is an effective repellent, but its action lasts 

 only for about a day." 



In 1916, experiments were made in Canada by A. W. Baker (6) with 

 a view to discovering a repellent which could be prepared cheaply by 

 the farmer and would, without detrimental effects of any kind, protect 

 cattle for at least two days from the attacks of Lyperosia and Stomoxys 

 well-known genera of blood-sucking Muscidae, of which several 

 species are found in Africa. After several trials, it was found that the 

 following mixture gave good results in the proportion of 1 to 2, 1 to 3, 

 and 1 to 4 of water : 1 gal. fish oil, 1 gal. kerosene, 1 gal. slightly 

 sour milk, 6 oz. oil of citronella. The cost of thoroughly spraying each 

 animal from horns to hoofs is stated to work out at about one farthing. 



In India, according to Cross (33), citronella oil, used alone, prevents 

 Tabanids and Stomoxys from attacking camels for a few hours, but has 

 no repellent action after 17 hours. Castor oil was found to have no 

 effect against either Stomoxys or Tabanids when only one pint per 

 camel was used, but at the rate of four pints per camel prevents 

 attacks by these flies for three days, and gives partial immunity for 

 about two days longer. This treatment, however, is too expensive 

 to be of practical use. 



It may be noted that in an experiment carried out by Simpson (144), 

 in the Gold Coast, with various oils and essences smeared over the 

 bodies of natives employed by him to collect Tsetse-flies,* the only 

 substances that appeared to act as deterrents were beechwood creosote 

 and beechwood oil. 



