THE MICROSCOPE AND INSECT LIFE 



their various parts, legs, feet, wings, etc., by un- 

 skilled hands and they must be examined whole. 

 Perhaps you may think that an insect will be too 

 big an object for your microscope. Indeed there 

 are some insects which measure nearly a foot in 

 length, but there are, on the other hand, beetles 

 no longer than one hundredth part of an inch. 

 When we examined the house-fly it is not unlikely 

 that we found some minute creatures living upon it. 

 None of these is likely to be an insect, but as they 

 are closely related we may mention them here. 

 Beneath the wings of the housefly there are often 

 minute, red, six legged young mites, all eagerly 

 sucking the juices of their host. Because they aye 

 six legged we may be led to think that they are 

 insects, for the entomologist knows that the true 

 insect, in its adult form, never has more than six 

 legs. These mites, however, later in life, drop from 

 the fly and by developing another pair of legs ap- 

 pear in their true colours. Various other mites, 

 including cheesemites, may be found clinging to the 

 house fly, in fact it is by the aid of these insects 

 that cheesemites are often carried from cheese to 

 cheese. One of the most curious parasites of the 

 house fly must be sought upon its legs. If the search 

 is successful, curious, reddish-brown creatures, 

 armed with formidable pincers, and strangely remi- 

 niscent of miniature lobsters, will be found clinging 

 thereto. They are called chelifers and their home is 

 the manure heap, so that their presence shows us 

 only too well where our friend the fly has recently 



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