xxni 



INSECT A : DIPTERA 



351 



ently fixing itself by the sucker-like tips of four sijccial 

 tubular hairs present on the last segment of .the abdomen 

 (Fig 274, a). It seems able either to suspend itself by these 



nat siz« 



FiQ. 273.- 



'us (pnpa). 



Fig. 274. 



Tail segments enlarged to show 

 the stiff hairs, li, and also 

 the tubular sucker hairs, a. 



in the position shown in Fig. 273, or it will lie at the bottom 

 of the water with the hairs fixed and the thorax bent right 

 over the abdomen. Occasionally, it will suddenly straighten 

 the body and throw back the head and thorax for a brief 

 moment, but except for this movement, it will hang or lie 

 motionless for hours.^ 



Imago. 



From this pupa 

 the fly emerges at 

 the surface of the water, and 

 soon the female deposits on 

 some floating object a little, 

 flat, circular mass of jelly, in 

 which are embedded a number 

 of long, oval eggs, arranged in definite rows, which hatch 

 out in due time. 



Fig. 27.5. — Tanypus (imago). 



' I was unable in my specimens to see tlie abdominal suckers referred to 

 by Professor Miall (Aquatic Insects, p. 154) and J. Meinert. 



