THE DANGER OF FLIES 



And Moses said, Behold, I go out from thee, and I will entreat 

 the Lord that the swarms of flies may depart from Pharaoh, from 

 his servants, and from his people, to-morrow. — Exodus. 



It is one of those facts which not unfrequently occur 

 in science that we know less about the life-history and 

 habits of the commonest insects than we know about 

 scarce and remote species.' For instance, the life- 

 history of the common house-fly, one of the most 

 widely distributed insects in the world, is as yet very 

 incompletely known. 



It was Linnaeus who first described this insect and 

 named it Musca domestica, and de Geer who, in the 

 middle of the eighteenth century, first described its 

 transformation. In 1834 Bouchd described the larva 

 of the insect as living in the dung of horses and fowls. 

 In 1873 the well-known American entomologist, A. S. 

 Packard, reinvestigated the question, and L. O. 

 Howard has recently written on the subject. In our 

 own country C. Gordon Hewitt is publishing a mono- 

 graph on the house-fly, which will, when completed, 

 fill a long-felt want. Packard noted that in the August 

 of 1873 the house-fly was particularly abundant, 

 especially in the neighbourhood of stables. He was 

 able to observe the insects laying their ova in clumps 

 containing some 120 eggs in the crevices of stable 

 manure, ' working their way down mostly out of sight.' 

 The eggs hatched in about twenty-four hours, but he 

 noticed that those hatched in confinement required 



174 



