VIII 



MAY-FLIES 



319 



Polymitarcys— the lateral filaments of the larva are 

 fringed on the inner 

 side only.] 



" The recently emerg- 

 ed fly," says De Geer, 

 " settles on trees, plants, 

 walls, &c., near the water 

 which harboured the 

 larva. Here it fixes itself 

 by the hooks of the feet, 

 usually with the head 

 downwards, and rests 

 until the last or sub- 

 imaginal moult is at 

 hand.^ 



" The fore legs of the 

 male fly are very long, 

 as in other Ephemerae, 

 and raised from the 

 ground, so that they 

 look like antenna;. They 

 can be brought down 



1 In some Ephemcridce I 

 have seen the sub-imago 

 (imago enclosed in a trans- 

 parent skin) emerge from 

 the larval skin under water, 

 and float up. In other cases 

 (Baetis fluminum, for in- 

 stance) the larva creeps out 

 of the water, like Perla, and 

 the cast larval skin is left on 

 the shore. 



Fir,. 93. — Larva of Ephemera vulgata, X 5. 

 From Vayssiere. The fore and mid legs 

 are cut short, and all the tracheal gills of 

 the left side, except the first, are cut 

 across. A small tuft of hairs appears 

 close to each gill, which probably serves 

 to keep off foreign particles. 



