DON ATA 



79 



Family Libellulid^e 



This is a large family including many of our commonest and best- 

 known species of dragonflies; many of them are familiar figures flying 

 over ponds and ditches and by roadsides. Most of them are of well- 

 sustained flight, and are seen continually hovering over the surface of 

 still water; this suggested the common name skimmers which has been 

 applied to them. 



Suborder ZYGOPTERA * 



The Damselflies 



The damselflies differ so much from the dragonflies and are so much 

 like each other that they also constitute a well-defined suborder, Zygop- 

 tera, of the Odonata. 



The two pairs of wings of 



the damselflies are similar in 



form and are either folded 



parallel with the abdomen when 



at rest or are uptilted in a 



vertical position (Fig. 128). 



The head is small and the eyes 



project on each side while the 



females possess an ovipositor 



by means of which they place 



their eggs in the stems of 



aquatic plants sometimes be- 

 neath the water. 



Unlike the dragonflies, the 



damselflies are comparatively 



slow and feeble of flight al- 

 though they are graceful in 



their movements. They are 



found along the margins of 



streams and ponds in which the 

 nymphs pass their lives. 



Many of the damselflies are very attractive because of their bright 

 blue or green metallic colors. 



The nymphs of the damselflies are slender, long-bodied creatures 

 which cling to weeds in the water (Fig. 129). The abdomen is narrow 

 and bears at the caudal end three flat, leaf -like tracheal gills set on edge 

 in a vertical position. 



There are two families of the damselflies, the Agrionidce and the 

 Ccenagrionidce. 



Family Agrionidce 



Here belong the most -beautiful of our damselflies, whose metallic 

 blue or green colors are sure to attract attention. They are feeble in 

 * Zygoptera: zygon (^vyov), yoke; pier on (wTepov), a wing. 



Fig. 128. — A damselfly. 



Fig. i2g. — Nymph of 

 a damselfly. 



