ORDER DIPTERA: SCHIZOPHORA: THE MUSCOIDEA 149 



The species may be hairy or not, but they are never 

 thickly covered with bristles and never have discal bristles 

 (see p. 41) on the abdomen. The arista is almost always 

 plumose to the tip. 



From our practical point of view it is convenient to deal 

 with the Muscidse in two lots, according to the manner in 

 which they affect man. 



I. Muscidce which do not, as Adults, suck Blood. 



Of these some, like the house-fly and blow-fly, are harm- 

 ful to man by carrying infection directly and mechanically, 

 or by polluting food and drink, in the ways already men- 

 tioned (p. 32). 



Others, like the green-bottles and the notorious screw- 

 worm fly, also may deposit their eggs in foul wounds or in 

 the natural orifices of the body of man and animals, whence 

 their larvae (maggots) may burrow into the tissues, and if 

 they get into the bony cavities of the head may do mortal 

 hurt. 



The maggots of one genus {Cordylohid) are habitually 

 subcutaneous parasites of man and domestic animals. Those 

 of another genus {Auchmeroniyici) have much the habits of 

 bed-bugs, hiding by day and coming out at night to suck 

 the blood of sleepers. 



With regard to the species whose' maggots get into 

 wounds or invade the natural openings of the body (com- 

 monly the nostrils), it need hardly be mentioned that they 

 are not likely to get a footing in healthy and vigorous adults 

 of clean habits. The sufferers are generally either careless 

 or dirty people, or lepers, or wounded men who have been 

 neglected, or people with very foul breath — incompetent 

 people, in short, whose odour also is so sufficiently like that 

 of the decomposing matter in which the fly naturally lays 

 its eggs as to mislead the insect. The treatment for 

 maggots that have burrowed from the nasal passages into 

 the sinuses of the head, devouring all before them, is free 

 and frequent irrigation with some powerful and volatile anti- 

 septic lotion, or with a strong solution of quassia and salt ; 

 chloroform-water is recommended by some, or an emulsion 

 of chloroform and turpentine in a watery solution of boracic 



