MYIASIS— ITS PREVENTION AND TREATMENT 207 



producing pure water. Where it is essential that water must be taken 

 from streams care should be exercised not to drink near vegetation. 



Use of Screens. — Proper screening of houses will do much to protect 

 foods after preparation from infestation, although some of the small 

 forms can not be kept out in this wa}'. A coarser mesh than 16 per inch 

 should not be used. Tlie use of screened toilets of course can not be too 

 strongly emphasized. 



Cleanliness and Careful Habits. — Many infestations of the digestive 

 system and genitalia could be avoided by not sleeping in unscreened places 

 in an exposed condition. Prompt attention to infants is important. 



SPECIES INFESTING HEAD PASSAGES 



Infestations in Animals. — The parasitic forms are very difficult to 

 control and no very satisfactory control measures have been devised. 

 Nearly all of the recommendations made are of little value. Some of 

 these consist of the use of repellents in the case of sheep to protect 

 them from infestation by Oestrus ovis. Pine tar is most frequently used 

 and this is applied by the sheep themselves. Holes in logs are used for 

 salting and the sides are smeared with tar. The provision of plowed 

 furrows where the sheep can protect their noses probably gives some 

 relief. For very valuable animals screened pens are no doubt warranted, 

 the animals being placed in these during the portion of the day when 

 the flies are most active. There seems to be considerable difference in 

 eff'ect of attacks on breeds. Attempts to remove the larvae from the nose 

 by causing sneezing or with fumigants are more likely to drive the larva3 

 deeply into the head than to remove them. Trepliining the skull and 

 removing the larvae in that way may give some relief but is usually not 

 advisable as other infestations are likely to follow and all the grubs 

 can not be reached. Destruction of adults has been advocated and is 

 especially applicable to plains areas, as in such places flies are inclined 

 to congregate on any objects which extend well above the ground. The 

 flies assemble on such objects and remain there except during the warmer 

 part of the da}'^ and many can be killed. 



]\Iany of the control measures suggested for the control of the sheep 

 bot can be used against the horse infesting species, Rhvnoestrus pur- 

 pureus. It might also be possible to utilize nmzzles similar to tliose advo- 

 cated for the horse bots to protect against infestations from tliis species. 



Infestations in Man. — Infestations of man are so infrequent that pre- 

 ventive measures need receive little attention. Where such infestations 

 either by the sheep head maggot or horse head maggot arc common 

 the use of nets on tlic hats similar to those used by apiarists would 

 give protection. jMedical attention should be given promptly for re- 

 moval of larv,T, especially if in tlie eye. 



