n8 The Under-Water World 



a length of over four inches and acts as 

 the breathing apparatus, being provided 

 at the extremity with a rosette of fila- 

 ments. The pupa is enveloped by the 

 larval skin, the larva when fully grown 

 leaving the water and burying itself in 

 the soil. The adult fly is very bee-like 

 in appearance. 



One does not usually associate the 

 moths with an aquatic existence, but 

 there are a few species whose larvae feed 

 on the leaves of water plants, protecting 

 their weakling bodies by means of cases 

 or sheaths formed of small pieces of 

 plant tissue and silk ; these cases much 

 resemble those of the caddis- worms. 

 The moths known in this country as the 

 " China Marks " have this habit. 



The important order, Hymenoptera, 

 containing the bees, wasps, ants, etc., 

 has a few aquatic representatives. These 

 belong to the parasitic group. They in- 

 clude the extremely small " Fairy Flies," 



