284 SANITARY ENTOMOLOGY 



powder are not obnoxious to most persons and are very effective in freeing 

 a room of mosquitoes. The powder slightly moistened and moulded into 

 a candle will burn slowly like punk. The essential oil of the powder may 

 be volatilized by placing on a metal screen above a lamp chimney. The 

 odor is only slightly perceptible and not unpleasant. 



For protection of the body, camphor, oil of citronella, oil of cassia, 

 and other essential oils are found efficacious. Howard, Dyar, and Knab 

 recommend as the best in their experience: 



This may be rubbed on the clothes or body. A few drops on a bath 

 towel hung over the bed will keep Culex pipiens away for a whole night. 

 Graybill lists many repellents against flies which have been tried on 

 apimals. The most successful substances tried by him were 50 per cent 

 pine tar in cotton seed oil, or 10 per cent oil of tar in cotton seed oil, 

 when applied lightly. Fish oil is a very effective repellent. Bishopp's 

 fish oil repellent is very effective in keeping flies from livestock when 

 applied lightly. It consists of : 



Fish oil 1 gallon 



Oil of tar 2 ounces 



Oil of pennyroyal 2 ounces 



Kerosene Yo pint 



Mosquito nets for the bed are used in many parts of the South where 

 the buildings are unscreened. Campers who sleep in hammocks may 

 easily arrange a good sleeping net by tying a rope to the hammock sup- 

 ports and hanging from this a tent-shaped net which can be fastened at 

 the ends and tucked in beneath the blankets. 



Hegh illustrates mosquito bars for tent coverings, for tent doors, 

 and soldiers' cots, and also a mosquito bar fastened inside a soldier's 

 small field-tent so that the sides of the tent can be raised to give air. 

 Various type of protective headgear have been described for troops in 

 tropical countries, two of which are illustrated by Hegh. Simpson illus- 

 trates a new headgear invented by his wife, which can be worn by day 

 and at night. 



The references cited below are worthy of study in connection with 

 this lecture. There are many other works in all languages on the 

 special problems of different countries, most of which are listed by 

 Howard, Dyar and Knab. 



