92 
THE STUDY OF INSECTS . 
parallel with the abdomen when at rest (Fig. 99) or are up- 
tilted. The head is transverse, each eye being borne by a 
lateral prolongation of the head. The females possess an 
1—nympa oi a no. ioi.— 
damsel-fly. Tracheal gill 
of nymph of 
damsel-fly. 
ovipositor by means of which the eggs are placed in the 
stems of aquatic plants, sometimes beneath the surface of 
the water. 
The name of the suborder is from the Greek zygon , 
yoke, and pteron , wing; it probably refers to the fact that 
the wings are brought together when at rest. 
Unlike the dragon-flies, the damsel-flies are compara¬ 
tively feeble in their flight. They are found near the 
margins of streams and ponds, in which the nymph stages 
are passed. 
The nymphs of damsel-flies (Fig. 100) possess leaflike 
tracheal gills at the caudal end of the body. One of these 
is represented greatly enlarged by Fig. 101. 
