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to draw the attention of colonists in Tropical Africa to these investi- 

 gations, in order that similar trials may be made in regions where stock 

 is subject to the attacks of Tsetse-flies. While the destruction of the 

 insects themselves would certainly be the most effective mode of attack 

 in a campaign against Glossina, the discovery of a really serviceable 

 repellent, costing little, easy to apply, and forming a barrier, temporary 

 though it be, between the fly and its victim, would render an appreciable 

 service to stock-raising and agriculture in Tropical Africa. With this 

 end in view, we give below a few extracts from an extremely useful 

 little brochure (59) published not many years ago in the United States. 



" There are almost innumerable homemade and proprietary external 

 remedies for repelling flies. They contain various substances that are 

 distasteful to the insects. Many of them contain strongly odoriferous 

 ingredients that have a repelling influence on flies. The qualities to 

 be sought in a satisfactory repellent are : Absence of toxic and other 

 detrimental properties when applied externally to animals ; a marked 

 repellent action on flies ; and a duration of this action for a reasonable 

 length of time. A common defect of many otherwise rather good 

 repellents is the very short period during which they are effective. 

 Some repellents are undoubtedly toxic and must be used with care. 



" Repellents as a rule are in the form of liquids, and may be applied 

 by means of a dipping vat, a pail spray pump, an atomizer such as that 

 commonly used in gardens and greenhouses for applying insecticides 

 to plants, or by means of a rag or a paint brush. The method employed 

 necessarily depends to a very large extent on the number of animals 

 to be treated, the physical character and toxicity of the preparation, 

 its cost, and the individual preference of the farmer or stockman. Some 

 preparations, either because of their cost or their toxicity, or for some 

 other reason, are not adapted for use in a dipping vat or for application 

 by means of a spray pump. Others may be applied by any one of the 

 methods mentioned." 



" The powder remedies that have been used are pyrethrum powder 

 and tobacco powder. 



" Various oils, emulsions of oils, and mixtures of oils are used in 

 repelling flies. Crude petroleum, cottonseed oil, fish or train oil, and 

 light coal-tar oil may be used pure. Jensen (1909) recommends for 

 dairy cows an emulsion of crude petroleum containing an admixture of 

 powdered naphthalin. 



" Fish oil is rated as one of the best repellents, and has been used 

 alone and in combination with various other substances. Other 

 substances that have repellent qualities and that have been used in 

 various mixtures are pine tar, oil of tar, crude carbolic acid, oil of 

 pennyroyal, and kerosene. 



" Jensen's formula 1 is said to protect cows for a week. The pro- 

 tective action of fish oil is stated to range from less than two days 

 (Parrott, 1900) to six days. Moore's formula 2 is said to protect for two 

 days. This mixture is safe when applied lightly with a brush, but not 

 when applied liberally with a pail spray pump. 



" Laurel oil is a very effective repellent. Mayer (1911) found that 

 the protection lasted from 2 to 12 days. The oil when used pure has 

 an irritating effect unless it is applied lightly. According to Mayer the 

 irritating effect may be overcome by combining it with linseed oil in 



1 Common laundry soap, 1 Ib. ; water, 4 gals. ; crude petroleum, 1 gal. ; 

 powdered naphthalin, 4 oz. 



2 Fish oil, 100 parts ; oil of tar, 50 parts ; crude carbolic acid, 1 part. 



