144 
HALF HOURS WITH INSECTS, 
[Packard. 
Ephydra, with its rather short, thick tubes and fleshy feet, 
clambers over green sea weeds in salt pools removed above 
the reach of ordinary tides, or lives in the brine pools of 
Illinois, or the salt lakes of the West. The aquatic larva 
of one of the Tipulids or crane flies (Ptychoptera) has a 
long respiratory tube, while in the pupa there is one attached 
to the head and much longer proportionally than in the lar¬ 
val Helophilus. 
Among those larval flies which are obliged to ascend to 
the surface to breathe, is the young Mosquito (Fig. 109 ; a, 
fig. los. 
Helophilus larvae (after Figuier). 
larva; b, pupa; a, paddles at end of body of pupa). Its 
body is beautifully adapted for going through its aquatic 
evolutions. The head and thorax are so large and bulky 
that it cannot ascend and lie motionless in a horizontal 
position, as in the young Anopheles, which lies before us in 
a dish as we are writing ; but it hangs head downwards and 
breathes by means of a spiracle lodged in one of the large 
tubes into which the end of the body subdivides, the posi- 
1G 
