471 



The nymphs of this species may be taken in the clearer and 

 swifter streams of Ilhnois, though not often in very great numbers. 

 The adults do not wander far from the habitat of the nymphs and 

 their period of flight seems to be largely limited to a short time in 

 early summer. The species is supposed to have a northerly distribution, 

 but has been taken near the southern boundary of the state. Several 

 nymphs taken at Urbana early in June emerged June lo, 191 5, and 

 subsequent collections of adults show that the insect flies until early 

 fall, although the period of maximum abundance lies between the 

 middle of June and the middle of July. 



Specimens have been seen from Havana, Muncie, Oregon, Peoria, 

 Urbana, Cook County, and McHenry County. 



Genus Hktaerina Hagen 



The nymphs of this genus have shallow mental clefts, and have 

 the margins of the pronotum prominently elevated, and the margins of 

 the lateral gills marked with black or dark spots. 



The adults are characterized by cross-veins within the basilar 

 space and by pale stripes on all of the pleural sutures of the thorax. 



KJEY TO Species 



MALES 



a. Bases of hind wings tinted with carmine similar to that of the front 



wings; legs striped, buff and black or dark brown americana. 



aa. Bases of hind wings tinted with brown ; legs entirely dark, not 

 striped titia. 



FEMALES 



a. Mesepisterna and mesepimera of the thorax without elongate spots of 



green ; uniform bronze americana. 



aa. Mesepisterna and mesepimera of the thorax with elongate spots of 

 green titia. 



Hetae;rina AMERICANA Fabricius 



Nympli. — Color, brown or greenish. 



Head pentagonal, about as long as broad ; proximal segments of 

 the antennae nearly twice as long as all the remaining ones together ; 

 eyes black or dark; labium (Fig. 9) thickset, the cleft of the median 

 lobe hardly extending proximad of the articulations of the labial palpi ; 

 labial palpi with three end-hooks and five or six small setae at the 



