244 



Marvels of the Universe 



Photo hy'\ 



[E. J. Spina. 



THE HOUSE-FL^'. 



The Fly is here shown sufhcienlly magnified to make its parts distinct. Note the spread- 

 out tongue " and compare it with the corresponding part in the photo below. 



'''"'''> ''y'i [B. J. Sfiitta. 



THE STABLE FL^■. 



The great difference in the "tongues" of the two Flies that are so frequently 

 confused is here made very clear. The lancets with which this Fly stings are shown 

 a little to the left of the tongue. 



are difficult to get, for when 

 the Fly is obtained, it is not 

 easy to keep alive, as it nuist 

 have fresh blood upon which 

 to live. 



The egg of the House Fly 

 hatches in about twenty-four 

 hours, when the grub puts in 

 an appearance. It remains as 

 such about seven or eight days, 

 changing its skin several times 

 as it increases in size, until 

 reaching finality when about 

 half an inch in length. The 

 grub now changes into a chry- 

 salis, which is smaller than 

 the grub, being only about a 

 quarter of an inch in length. 

 Having remained three or four 

 days, the case cracks, and out 

 emerges the complete Fly. 

 Mention should here be made 

 that it is a misconception to 

 suppose that flies grow. No 

 growth takes place in their life 

 save at the grub period, when 

 they change ■ their skins, as 

 already explained ; hence the 

 smaller variety of fly, occasion- 

 ally and rathei: rarely seen 

 upon the window-panes, is not 

 the House Flj? in "the act of 

 growth, but a smaller_species. 



Before quitting the subject, 

 we must not omit to mention 

 the marvellous foot of this little 

 insect, shown on page- 238. 

 Here it is seen to consist of 

 two horn-like projections at- 

 tached to the end of the leg, at 

 the base and sides of which are 

 seen the two pads. It is the 

 pads which are so wonderful, 

 and their construction merits 

 more than a passing attention ; 

 for it is by means of these little 

 arrangements that the insect is 

 able to hold on the ceiling or 

 upon glass, even when upside- 



