MAY-FLIES AND THEIR NEIGHBOURS 221 



Of the caddis-flies the British Isles have no 

 fewer than 1 50 species. The larger of these insects 

 be jJn to fly as ni^ht approaches, being of nocturnal 



Fig. 146. Larva of the alder-fly. 

 x 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 

 tiny scales arranged on each side as in the case 



