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 ephemeros , 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- 
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 . 
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