Insect Study 407 



nibbles it. But as a pair of military brushes, its hind feet are 

 conspicuously efficient ; they clean each other by being rubbed together 

 and then they work simultaneously on each side in cleaning the wings, 

 first the under side and then the upper side. Then over they come and 

 comb the top of the thorax; then they brush the sides, top and under 

 sides of the abdomen, cleaning each other between the acts. Who, after 

 witnessing all this, could believe that the fly could leave any tracks on our 

 food, which would lead to our undoing! But the house-fly, like many 

 housekeepers with the best intentions in the matter of keeping clean, has 

 not mastered the art of getting rid of the microbes. Although it has so 

 many little eyes, none of them can magnify a germ so as to make it visible; 

 and thus it is that, when feeding around where there have been cases of 

 typhoid and other enteric diseases, the house-fly's little claws become 

 infested with disease germs ; and when it stops some day to clean up on our 

 table, it leaves the germs with us. Thus our only safety lies in the 

 final extermination of this little nuisance. 



It is astonishing how few people know about the growth of flies. 

 People of the highest intelligence in other matters, think that a small fly 

 can grow into a large one. A fly, when it comes from the 

 pupa stage, is as large as it will ever be, the young stages 

 of flies being maggots. The house-fly's eggs are little, 

 white, elongated bodies about as large as the point of a 

 pin. These are laid preferably in horse manure. After 

 a few hours, they hatch into slender, pointed, white 

 maggots which feed upon the excrement. After five or 

 six days, the larval skin thickens, turns brown, making _ 

 the insect look like a small grain of wheat. This is the Tkin of fly 

 pupal stage, which lasts about five days, and then the skin enlarged. ' 



bursts open and the full-grown fly appears. Of course, 

 not all the flies multiply according to the example given to the children. 

 The house-fly has many enemies and, therefore, probably no one hiber- 

 nating mother fly is the ancestress of billions by September; however, 

 despite enemies, flies multiply with great rapidity. 



I know of no more convincing experiment as an example of the dan- 

 gerous trail of the fly, than that of letting a house-fly walk over a saucer 

 of nutrient gelatin. After three or four days, each track is plainly visible 

 as a little white growth of bacteria. 



Much is being done now to eradicate the house-fly, and undoubtedly 

 there will be new methods of fighting it devised every year. The teacher 

 should keep in touch with the bulletins on this subject published by the 

 United States Department of Agriculture, and should give the pupils 

 instructions according to the latest ideas. At present the following are 

 the methods of fighting this pest : Keep the stable clean and place the 

 manure under cover. All of the windows of the house should be well 

 screened. All the flies which get into the house should be killed by using 

 the commercial fly papers. 



