10 INTRODUCTION 



the food, they infect the food, and the children die. 

 It is not the food which kills our infants but the flies' 

 mark upon it. Surely it is time we did something to 

 prevent or reduce this pest. 



The reduction of domestic flies is a simple matter, 

 but it must be persevered with. Flies are best attacked 

 while they are in the larval or maggot stage of their 

 existence, for then it is easy to destroy them in large 

 numbers. It is, of course, also easy to trap or kill 

 many of the flying insects in a room ; but then more 

 will fly in to take the place of the dead ones. Whereas 

 if the larvae are dealt with, instead of accounting for 

 at most a few hundreds, they can be killed in their 

 thousands. Besides, prevention is better than cure. 



The house-fly breeds in all sorts of filth, but stable 

 manure is the commonest lair for this insect. The 

 female fly likes to lay her eggs here, and in the horse- 

 dung the fly-maggot or grub lives for five days and 

 then becomes a chrysalis or nymph (pupa). This stage 

 commonly lasts another five days, after which the 

 fully developed flying insect or imago so familiar to us 

 all emerges to do its deadly work in the world. It is 

 during the former stages that the insect can be found 

 in its numbers collected together, and it is during these 

 stages that it can be easily destroyed, for it gives 

 us ten days in which to look for it while it is crawling, 

 and to take such measures as we conveniently can 

 against it. It is a simple process. All manure, ash- 

 bins, dust-heaps, privies, etc., should be inspected once 

 every week regularly for fly-larvae and the material 

 containing the larvae destroyed. If this was done in 

 every town and village regularly and perseveringly 

 there would soon be a reduction of flies, and with the 

 flies would go much typhoid fever, and many infants' 



