GNATS, MIDGES, AND MOSQUITOES 227 



usually remains in his native haunts, not invading our 

 apartments ; for it must be remembered that these flies, 

 like those treated of before, pass their early stages out 

 of doors, and enter our houses only when fully grown. 

 The straight cylindrical spike, projecting from the head, 

 though itself no thicker than a hair, is a tube, or rather 

 trough, terminated by two small fleshy lips, the dwarfed 

 representatives of the two large folding leaves which 

 terminate the proboscis of the blow -fly. This tube 

 represents the labium of the normal insect's mouth, and 

 concealed within it lie the much finer piercing organs ; 

 for the so-called " bite " consists really of a boring and 

 sucking operation. Along by the upper slit of the 

 trough lies a long bristle-shaped organ, which represents 

 the labrum or upper lip j and of course all the rest of 

 the mouth organs, except the palpi, lie between this and 

 the labium, i.e., in the trough of the latter. The man- 

 dibles and maxillae, which in insects that feed on solid 

 food are efficient biting weapons, are here replaced by 

 four fine-pointed, needle-like bristles, the maxillae being 

 further barbed at the tip like a savage's spear, and the 

 mandibles slightly broadened into a lancet-shaped tip. 

 Besides these, another piercing bristle is found, which is 

 an appendage of the labium itself. Thus there are no 

 less than six boring organs, all contained within a sheath 

 which is itself almost of hair-like fineness. The sheath 

 itself, like so many other parts of the body, is beautifully 

 ornamented outside with abundance of battledore-shaped 

 scales. At its base are two short jointed organs, the 

 maxillary palpi, representatives of the two un jointed 

 red clubs which are such conspicuous appendages of the 

 mouth of the blow-fly. This straight, unjointed spike 

 is, at first sight, as different as could well be imagined 

 from the elbowed, broad-tipped apparatus with which the 



