PARASITES OF FLIES i8i 



is inclined to think it is the larval form oi Dispharagus 

 nasutus (Rud.). What the further history of this 

 parasite is we do not conclusively know, but, judging 

 by analogy — and in the case of the grosser parasites it 

 is not always wise to do that — the nematode probably 

 develops in some higher animal which eats the fly. 

 Plana brings forward a good deal of evidence that this 

 is the domestic fowl. 



Another parasite which attacks flies is the fungus 

 or mould Empusa muscce, whose growth is fatal to the 

 insect. The hyphae penetrate into the body, and as 

 they grow weaken the fly until it is unable to lift a 

 leg, but remains glued by its viscid feet to the object 

 upon which it rests. The fungus spreads and radiates 

 out in all directions, covering the fly as with a velvety 

 pile, and giving off countless minute spores, which are 

 blown away, to alight, if they are lucky, on a further 

 victim. 



I think enough has been said to prove that flies are 

 a very real danger to our community. I have re- 

 frained from giving the appalling statistics of our 

 infant mortality, partly because of the difficulty of 

 discriminating between the claims of the flies and 

 those of other agencies which affect the lives of our 

 babies — e.g., the insurance companies which do a 

 large trade in insuring infants. Legislation has not 

 attempted to control the latter. Sanitation might do 

 much to destroy the former. In well-administered 

 towns slaughterhouses no longer ' fill our butchers' 

 shops with large blue flies '; they have been replaced 

 by abattoirs, under proper inspection. Stables should 

 also be segregated or controlled. The practice of 

 backing the mansions of Berkeley Square by stable 

 yards should either be given up, or the manure-heaps 

 in which the flies breed should be under cover so 

 close as to prevent the access of the fly. A layer of 

 lime spread over the manure effectively prevents the 



