MAY-FLIES AND THEIR NEIGHBOURS 221 



01 the caddis-rties the British Isles have no 

 fewer than 150 species. TlTie larger of these insects 

 bejin to tly as ni_^ht approaches, being ot nocturnal 



Fig. 146. Larva of the alder-tly. 

 -. 3 diameters 



habits. Hence they may readily be mistaken for 

 moths. Their wings are semi-transparent and of 

 various .shades of brown, occasionally adorned with 

 markings, though they have not the innumerable 

 tinv scales arrano;ed on each side as in the case 



