MAY-FLIES— SPIDERS 373 



stage known as the sub-imago, when they emerge, and moult into the fully 

 developed insect. The common May-fly (Ephemera vvZgata), known to fly-fishers 

 in the sub-imago state as the " green drake," is over half an inch in length, brown 

 in colour, with three rows of spots on an orange-yellow body, the wings beino- 

 barred with brown, with a brown stripe on the front pair. Another species is 

 Palingenia virgo, which when full grown is about three-quarters of an inch lon<>-, 

 and often appears in such numbers that the multitude, as it dances and dies, looks 

 like falling snow. 



'y-' ■ <•*- v*i 



WHITE MAY-FLY. 



Among reeds by the edge of the water, as well as in woods, may 

 be seen the large wheel-shaped webs of the bank-spider (Tetragnatha 

 extensa), which belongs to the tribe of orb-spinners. This species has a long body 

 with legs twice as long, and is of a yellowish green colour, marked with a black 

 feather-like stripe down the middle. About double the size, occasionally attaining 

 the length of three-quarters of an inch, is the water-spider (Argyroneta aquatica), 

 which lives in fresh water all over Europe. This species, which is reddish brown 

 in colour, has the grey back dotted with rows of spots ; the males being lighter than 

 the females. These spiders, which feed on water-lice and insect-larvae, live in 

 hollow webs, about the size and shape of a pigeon's egg, with the aperture opening 

 downwards. From this they spin threads, attaching them to the surrounding plants, 

 and when diving they enclose the hind part of the body in an air-bubble, which is 

 carried down to fill the water-tight web with oxygen. The velvet-spider (Clvhiona 



