FLIES. 153 



vibrates the wings 440 times. A tired bee hums on 

 E, and vibrates some 330 times in the second. The 

 bee's contented hum, when in quest of honey, is A. 

 Thus there is really an expression of the emotions in 

 these insects ; and there is no better reason, after all, 

 why a fly or a bee should not give vent to its joy or 

 indicate its rage, than our neighbour the Gaul should 

 shrug his shoulders or turn out the palms of his hands. 



After a busy season, the flies leave the soul of the 

 housewife vexed and angry. She contemplates with 

 dismay the fly-blown paper, and the scratched and 

 eroded surfaces of her furniture and books. If it is 

 desired that the source of these destructive powers 

 should be seen, you have only to put the fly's tongue 

 under a low power of the microscope. This is the 

 organ which, when at rest, is bent up beneath the 

 insect's head. When it alights on the sugar, you can 

 see the fly unfold its proboscis for predatory purposes, 

 and scrape the toothsome morsel. The end of the 

 tongue actually unfolds into a couple of broad fan- 

 like leaves, serving at once as raspers and suckers. 

 By means of this rough file-like expansion of the 

 tongue, the fly works havoc with delicate surfaces, 

 and it is doubtless this proboscis which annoys and 

 tickles us when the insect pays those personal atten- 

 tions to which allusion has been made. The fact of the 

 tongue being an unruly member and a source of annoy- 

 ance finds a new interpretation in the case of the fly. 



Like the butterflies and beetles, the fly passes in 

 its development through what zoologists call a perfect 

 metamorphosis. In other words, it begins life as a grub 

 or caterpillar the baby flies are scornfully denominated 

 " maggots " then it becomes a pupa or chrysalis, and 

 finally emerges into the full-grown and winged insect. 



