406 Handbook of Nature-Study 



carry disease, like the mosquitoes, flies and fleas, must be a reconnaissance 

 for a war of extermination ; the fighting tactics may be given in lessons 

 on health and hygiene. 



Perhaps if a fly were less wonderfully made, it would be a less con- 

 venient vehicle for microbes. Its eyes are two great, brown spheres on 

 either side of the head, and are composed of thousands of tiny six-sided 

 eyes that give information of what is coming in any 

 direction; in addition, it has on top of the head, looking 

 straight up, three tiny, shining, simple eyes, which cannot 

 be seen without a lens. Its antennae are peculiar in 

 shape, but are evidently sense organs ; it is attracted from 

 afar by certain odors, and so far as we can discover, its 

 antennas are all the nose it has. Its mouth-parts are all 

 combined to make a most amazing and efficient organ 

 for getting food ; at the tip are two flaps, which can rasp a 



Head of -fly show- su bstance so as to set free the juices, and above this is a 

 me eyes, antennas 1,1 i i 1 ,1 11 ,1 



and mouth- tube, through which the juices may be drawn to the 



parts. stomach. This tube is extensible, being conveniently 



jointed so that it can be folded under the "chin" when 



not in use. This is usually called the fly's tongue, but it is really all 



the mouth parts combined, as if a boy had his lips, teeth and tongue, 



standing out from his face, at the end of a tube a foot long. 



The thorax can be easily studied ; it is striped black and white above 

 and bears the two wings, and the two little flaps that are called balancers 

 and which are probably remnants of hind wings which the remote ances- 

 tors of flies flew with. The fly's wing is a transparent but strong mem- 

 brane strengthened by veins, and is prettily iridescent. The thorax 

 bears on its lower side the six pairs of legs. The abdomen consists of five 

 segments and is covered with stiff hairs. The parts of the leg, seen when 

 the fly is walking, consists of three segments, the last segment or tarsus 

 being more slender, and if looked at with a lens, is seen to be composed 

 of five segments, the last of which bears the claws; it is with these claws 

 that the fly walks, although all of the five segments really form the foot ; 

 in other words, it walks on its tip-toes. But it clings to ceilings by means 

 of the two little pads below the claws, which are covered with hairs that 

 excrete at the tips, a sticky fluid. Because of the hairs on its feet, the fly 

 becomes a carrier of microbes and a menace to health. 



The greatest grudge I have against this little, persistent companion of 

 our household is the way it has misled us by appearing to be so fastidious 

 in its personal habits. We have all of us seen, with curiosity and admira- 

 tion, its complex ablutions and brushings. It usually begins, logically, 

 with its front feet, the hands; these it cleans by rubbing them against 

 each other lengthwise. The hairs and spines on one leg act as a brush for 

 the other, and then lest they be not clean, it nibbles them with its rasping 

 disc, which is all the teeth it has. It then cleans its head with these clean 

 hands, rubbing them over its big eyes with a vigor 

 that makes us wink simply to contemplate ; then bob- 

 bing its head down so as to reach what is literally its 

 back hair, it brushes valiantly. After this is done, it 

 reaches forward first one and then the other foot of the 

 middle pair of legs, and taking each in turn between p oot O f i !0use .ft y 

 the front feet, brushes it vigorously, and maybe enlarged. 



