118 ARTHROPOD A 



ments at the end of the abdomen. The larvae of all the 

 species live in the water, feed upon vegetable matter, and 

 breathe by means of gill tufts. The larval life lasts from 

 one to three years during which large numbers are eaten 

 by fish. Metamorphosis to the adult form takes place in 

 May and June when the adults sometimes become so numer- 

 ous along the watercourses that the dead may be picked up 

 by the handfuls where the waves wash them up on the 



FIG. 139. May fly, twice natural size. 



shore. The pupa or nymph is active and much like the 

 larva in form, except wing pads are present. 



The adults take no food as the mouth parts are atrophied 

 and the alimentary canal is not fitted for digestion. They 

 usually live only a day or two. 



Dragon Flies (Odonata). All the numerous species of 

 this order have a similar life history which is easily studied 

 in any one of our dozen common kinds. The nymph or 

 larval stage may be found almost any time of the year in 

 mud at the bottom of ponds, and if large specimens are 

 removed to the aquarium in May and fed daily with fresh 



