V CADDIS-WORMS 255 



a dirty brown. The spiral in this last species consists 

 of a vast number of pieces, which increase in size by 

 imperceptible gradation. We have often to use a lens 

 to see that the band is not perfectly continuous. The 

 leaves of which it is is composed are usually leaves of 

 duckweed cut square. I believe that the fly of this 

 species carries its wings crossed one upon another 

 and laid horizontally. 



" All Caddis-worms find it difficult to live in water 

 which is contaminated, or in small vessels. They 

 will last longer out of the water than in a very scanty 

 supply or in foul water. M. Baron sent me several 

 larva; of a common species from Lugon to Paris by 

 post. When they arrived they had been five or six 

 days out of water ; however, they were still alive and 

 1 saw them walk." 



The Caddises exhibit something of that versatility 

 which characterise the whole class of Insects. Thus 

 we have species with moveable cases (the great 

 majority) ; species with fixed cases or retreats which 

 the larva quits at pleasure ; forms adapted to stagnant 

 water, others adapted to life in torrents. Some marine 

 species will be noticed in Chapter XII. Lastly, there 

 are terrestrial forms. The larvae of Enoicyla live in 

 moss at the foot of trees, often far from water. They 

 have no tracheal gills. The female flies are practically 

 wingless, an indication in other orders of Insects of 

 indiscriminate feeding and a plentiful supply of food. 

 F. pusilla occurs in England, and other species arc 

 known.^ 



The variety of the cases manufactured by Caddis- 

 ^ McLachlan, T7-ichoptera of the European Fauna. 



