CHAPTER V. 



Order EPHEMERIDA (Eph-e-mer'i-da). 



The May-flies. 



The members of this order have delicate membranous wings, 

 with a fine network of veins ; the fore wings are large, and 

 the hind wings are much smaller or wanting. The mouth- 

 parts are rudimentary. The metamorphosis is incomplete. 



The name of this order is from 

 the Greek word ephemeras, lasting 

 but a day. It was given to these in- 

 sects on account of the shortness of 

 their lives after reaching the adult 

 state.* The May-flies are easily dis- 

 tinguished from other net-winged in- 

 sects by the peculiar shape of the 

 wings and the relative sizes of the two 

 pairs (Fig. 94). 



The mouth-parts are nearly want- 

 ing, as these insects eat nothing in 

 the adult state ; the antennae are very 

 small ; the abdomen is long, soft, and 

 terminated by two or three many- 

 F.G. 94.-May.fly. jointed, thread-like appendages. In 



their metamorphoses these insects differ from all others in 

 molting once after they have acquired wings fitted for flight. 

 This order includes only a single family. 



* We have not adopted the name Plectoptera, which has been proposed 

 for these insects, on account of its similarity to Plecoptera. 



86 



