246 ENEMIES OF FLIES 



Howard (191 1, p. 85) states that Jones, in the PhiHppines, 

 found it impossible to raise flies unless the eggs and larvcX were 

 protected from ants, as the latter carried off the eggs, larvae, 

 and even the pupa;. He also states that in some parts of 

 America certain ants w^iich are attracted to horse manure 

 undoubtedly destroy some of the fly larvae in it, but that reliable 

 observers believe that they do not greatly reduce the numbers 

 of flies bred from the manure. In Saint Lucia, Nicholls (191 1, 

 p. 87) says that ants are the worst enemies of the larvae and pupae 

 of certain flies. " If these find a breeding place they will carry 

 off" all the larvae and pupae, and I have lost the entire number in 

 several experiments in this way." 



CHAPTER XXVI 



FLIES BREEDING IN OR FREQUENTING HUMAN FAECES 



Howard seems to be the only investigator who has carried 

 out systematic observations on the insects which breed in or 

 frequent human faeces, though others have recorded the presence 

 of the larvae of certain flies in this material. Howard has given 

 a useful summary of his v/ork in his book The Hoiisc-fly- 

 Disease carrier, from which this chapter is compiled. 



He obserV'Cd forty-four species of beetles and many hymeno- 

 pterous parasites, " all of the latter having probabK^ lived in the 

 larval condition on the larvae of Diptera or Coleoptera breeding 

 in excrement. Neither the beetles nor the hymenoptera, however, 

 have any importance from the disease-transfer standpoint. The 

 Diptera alone were the insects of significance in this connection. 

 Of Diptera there were studied in all seventy-seven species, of 

 which thirty-six were found to breed in human faices, while 

 the remaining forty-one were captured upon such excrement. 

 The following list indicates the exact species arranged under 

 their proper families." 



