477 



. Subfamily LESTINAE 



The nymphs of this subfamily are long, slender insects with very 

 slender legs. The median lobe of the labium is much contracted at 

 the base, the contracted portion being usually longer than the expanded 

 distal portion. The lateral keels of the abdomen are freciuently pro- 

 duced at the apex into a short spinule, and the gills are long, spatulate, 

 and usually without heavy marginal setae and with more or less brown 

 pigment. 



In the adults the nature of the wing venation is important. The 

 third median vein and the bridge unite with the R-M trunk nearer 

 the arculus than the nodus, and the stigma always surmounts two or 

 more cells. The long tibial and femoral setae, which are longer than 

 the distance between their bases, as well as the forcipate character of 

 the anal appendages of the male and the presence of a large ovipositor 

 with conspicuous sternites at the base of the cephalic pair of gon- 

 apophyses, are also important as diagnostic features. 



As a rule the adults are dull in color as compared with the Coen- 

 agrioninae and match the color of their usual environment extremely 

 well. 



Genus Lestes Leach 



The subfamily Lestinae is represented in Illinois by a single genus, 

 Lestes. The nymphs of this genus are recognizable by the character 

 of the labium. The proximal segment of the labial palpus always has 

 two processes mesad of the distal palpal segment, one of them resem- 

 bling a fork with the median tines broken off, the remaining process 

 consisting of a long non-bifurcate projection with a short heavy hook 

 at the distal end and minute teeth along the mesal margins, (Fig. lo). 



The adults are larger than most Coenagrioninae. Vein Mo, of 

 both wings, always arises distad of the second postnodal cross-vein and 

 the stigma rarely surmounts more than three cells. The arculus is 

 one-third or one-fourth the length of the caudal side of the cpiadrangle. 

 The wings are commonly held horizontally when the insect is at rest. 



Keys to Species 



NYMPHS 



a. Second segment of the labial palpus with three or four setae ; labimii 

 broad at the proximal end, the contracted portion of the median lobe 

 hardly longer than the expanded portion and about one-third as 



broad as the latter congener. 



aa. Second segment of the labial palpus with only two setae or very 

 rarely three (uncatus) ; labium narrow at the proximal end, the con- 



