A NI SOP TER A . 
91 
and their great compound eyes shining like gold or pre¬ 
cious stones. But for all their terrible names, dragon-flies 
are entirely innocent of any harm to mankind. They 
neither sew up people’s ears, as northern children think; 
nor bring dead snakes to life, as colored people in the 
South believe; but they are very fierce enemies to their 
insect kindred. Their long, narrow, closely netted wings 
are strong, carrying them swiftly ; and their jaws are 
powerful, and their appetites good ; so it is an unfortunate 
insect that falls in their way. The fact that they destroy 
mosquitoes has attracted much attention 
of late; but they feed upon a great variety 
of insects; and the larger species habitu¬ 
ally eat the smaller ones. 
The eggs of dragon-flies are laid in 
water or fastened to aquatic plants. The 
nymphs present a striking peculiarity of 
the respiratory system ; very large tra¬ 
cheae extend to the rectum, and their 
branches penetrate its wall and end in 
a complicated series of tracheal gills in 
the cavity of the rectum. The insect 
alternately draws water into this cavity 
and expels it; and thus the air in these 
trachea? is purified. This process also nympfrif^goTfly 
helps the insect in swimming, for the 
water may be expelled with such force that the whole body 
is sent forward. The full-grown nymph leaves the water 
to undergo its last molt; and the exuviae are often found 
clinging to objects near the water (Fig. 98). 
Suborder Zygoptera (Zy-gop'te-ra). 
The Damsel-flies. 
The damsel-flies differ from the dragon-flies in that the 
two pairs of wings are similar in form and are either folded 
