575 



The commonest species in Illinois, occurring practically where- 

 ever there is enough permanent water for the nymphs to live. The 

 adults appear early in May and continue to emerge until September 

 and possibly later. 



Specimens have been seen from Dubois, Carbondale, Golconda, 

 Havana, Lake Villa, Mahomet, Muncie, Peoria, Urbana, and Vienna. 



Genus Anomai^agrion Selys 



The nymphs of this genus are characterized by their unusually 

 small size, by the presence of a very slender tip to the gills, and by 

 the absence of setae on the lateral keels. 



The male adults are unique in having the stigma of the front 

 Aving removed from the margin and in the possession of a long process 

 on the dorsum of segment ten. The sternites at the base of the cephalic 

 pair of gonapophyses of the female are wanting, and the parameres of 

 the ninth sternum of the male do not reach the apex of the segment. 



Anomalagrion hastatum (Say) 



Nymph. — Color, green or buff. 



Head with the caudo-lateral angles rounded and without setae; 

 antennae with the first two segments dark brown, the remaining ones 

 light in color; second segment about as long as the first or slightly 

 longer; labium not extending caudad of the procoxae and about as 

 broad as long; mental setae four, lateral setae five. 



Thorax narrower than the head ; legs without dark rings and with 

 few setae, the tibiae with the usual apical scales ; wing-cases extending 

 nearly to the fourth abdominal segment. 



Abdomen uniform in color; lateral keels feebly developed and 

 without setae; gills (Fig. 60) lanceolate, with a long point; marginal 

 setae of the median gill consisting of a thick dorsal row, extending 

 about one-third the length of the gill from the base, and a scattered 

 ventral row at the base; ventral marginal row of setae of the lateral 

 gills slightly longer than the dorsal row of the median gill ; ovipositor 

 extending to the caudal margin of the tenth abdominal sternum. 



Measurements 



Length 9.5 mm. 



Length of abdomen 5.5 mm. 



Length of gills 4.5 mm. 



Width of gills 1.0 mm. 



Length of median lobe 1.6 mm. 



Width of median lobe 0.5-2.0 mm. 



