TRUE MIDGES (CHIRONOMID^) 473 



absence of night fogs and of low winter temperatures. The 

 adults will not Uve where there are continuous strong air currents. 

 These conditions limit the species closely to the deep-cut canyons 

 or " quebradas " (Fig. 53), between 3000 and 8000 ft. elevation, on 

 the west face of the Andes. There is certainly a remarkable 

 agreement between this distribution and that of Oroya fever. 



Control. — Sandflies are very difficult insects to deal with, both 

 on account of the small size of the adults and of the nature of 

 the breeding places. 



The only precaution that can be employed to keep the adults 

 out of houses during warm weather is the use of repellents. 

 Spraying mosquito netting with some repelling substance, such as 

 odorous oils, e.g., anise oil, eucalyptus oil, etc., or with a weak 

 solution of formalin, or, in fact, with any of the repelling sub- 

 stances mentioned in connection with mosquitoes, serves to keep 

 the insects out as long as the odor lasts. The insects are attracted 

 toward a light, and are therefore usually very abundant in Ughted 

 rooms on warm still nights. A gentle breeze or a current of air 

 from electric fans placed near the windows prevents their entrance 

 and, as has already been mentioned, upstairs rooms are practi- 

 cally immune. Personal protection can be obtained by appli- 

 cations of repellents. Townsend recommends equal parts anise 

 oil, eucalyptus oil and oil of turpentine in a boric acid ointment. 



It is almost impossible to destroy sandflies in their early stages. 

 Townsend thinks that the elimination of rubble fences in Peru 

 would reduce their numbers, at least locally, but it would be 

 far from a simple problem to destroy all possible breeding places, 

 even within a very small radius. In Europe, where stone and 

 cement are more extensively used than in America, the problem 

 is still greater. The earthquake ruins of Sicily, as has been 

 mentioned before, give unUmited breeding places. The large 

 numbers of these insects in parts of Egypt where such places are 

 not available indicate that damp cracks in soil may be utilized 

 as breeding places, and it would be obviously impossible to 

 eliminate these or to treat them thoroughly. 



True Midges (Chironomidae) 



General Account. — The family Chironomidae comprises a 

 large number of species of small flies, sometimes almost micro- 

 scopic, found all over the world. The larger ones quite closely 



