126 PISCATORIAL ENTOMOLOGY. 



devour many times their own weight in a single week, 

 and this is the case with all water- flies, whether 

 EphemericUz or Phyrandce (Up-winged or Flat-winged), 

 which feed only when in the larva and pupa state, 

 absorbing sufficient nutriment to sustain them during 

 the short and final stages of their life. They after- 

 wards appear in their new sphere, first as Duns, 

 secondly, as perfect imago or insects. 



As the eggs of the Ephemeridce had been deposited 

 in May, in the following February, whenever the state 

 of the water permitted, the first flies emerged from 

 their pupa case, rose to the top of the water, and 

 bursting yet another shell-like skin unfolded their 

 now perfect wings, and appeared as early Blue Duns. 

 A little more genial weather, and the Cockwing and the 

 Olive, from which the fly takes its name, was pre- 

 dominant, the lighter shades appearing as the nympha 

 gradually attained maturity, up to midsummer. April 

 saw the first instalment of Iron Blue, also March or 

 Spring Browns appeared, both being of a lighter shade, 

 and the latter a little smaller in dimensions, after the 

 lapse of a few weeks. Up to July the colour of the 

 Duns ranged in the precise ratio we have given, by 

 which time the whole of the nymphae had attained 

 maturity,* with the exception of a few of the Browns, 

 which rose in August, smaller still in size. To have 

 the whole season's supply of the Ephemeridce it is 

 necessary to take Spinners about May, and again in 



* Sometimes fresh-water shrimps, and other water insects found their 

 way into the hatching apparatus and made sad havoc ; but this evil is 

 evaded by placing a piece of the finest perforated zinc at the inlet. 



