Dragon-flies and Damsel-flies 91 



clear-winged true damsel-flies. Most of them are small, and many keep 

 so closely in low herbage or shrubby woodland that they attract little atten- 

 tion. A few of the longer-bodied and longer-winged forms, however, fly 

 in the open along the stream-banks or over the ponds. Some are strikingly 

 varied with black and orange or yellow, and all, whether brightly colored 

 or dull, are graceful and charming. There are at least a dozen genera of 

 Agrionids in this country, comprising about seventy-five species, but their 

 classification is too difficult to be undertaken by general students. Damsel- 

 flies deposit their eggs in the tissue of aquatic plants by cutting slits in the 

 stems with their sharp ovipositor. The nymphs are slender and elongate, 

 and can readily be known by the three caudal leaf-like tracheal gills. The 

 nymph stage of these forms is much shorter than with the true dragon-flies, 

 lasting usually probably but a few weeks, or at most two or three months. 

 When ready to transform the nymphs crawl out of the water and into the 

 low herbage on the stream or pond bank. I have seen scores of freshly 

 emerged damsel-flies rising from a few square yards of tall grass near a pond, 

 although it required close search to discover the nymphs, so well concealed 

 were they in the dense tangle. 



SUBORDER ANISOPTERA. 



KEY TO FAMILIES (IMAGOES). 



Antecubitals of the first and second rows mostly meeting each other; triangle of 

 fore wings with long axis at right angles to the length of the wings, triangle 

 of hind wing with long axis in direction of the length of the wing. 



LIBELLULID.E. 



Antecubitals of the first and second rows not meeting (or running into each other) 

 except the first and another thick one; triangles of fore and hind wings of 

 similar shape (Fig. 121). 



Eyes meeting above on middle line of head; abdomen with lateral ridges. 



/ESCHNID.E. 

 Eyes just touching at a single point or barely apart; abdomen without lateral 



ridges CORDULEGASTERID^E. 



Eyes distinctly separated; abdomen without lateral ridges GOMPHID^E. 



KEY TO FAMILIES (NYMPHS). 



Under-lip (labium) flat, not concealing most of the face, with jaw-like or oblong 

 side pieces (lateral lobes). 



Antennae 7-segmented, tarsi 3-segmented, climbing nymphs .. ^EscHNiDyE. 

 Antennas 4-segmented, the fourth segment rudimentary; fore tarsi 2-seg- 



mented; burrowing nymphs GOMPHID^E. 



Under-lip (labium) spoon-shaped, covering most of the face, when closed, with nearly 

 triangular side pieces (lateral lobes). 



Two stout teeth with a notch between them on the middle lobe of the under- 

 lip (labium) CORDULEGASTERIDJE. 



A single median tooth on the middle lobe of the under-lip LIBELLULID^E. 



