FIELD BOOK OF PONDS AND STREAMS 



Argia violacea. — This is the commonest species of this genus 

 in the eastern states (Fig. i68). The nymphs live in almost 

 everv^ kind of aquatic situation but prefer slow streams and 

 coves. The species is named from the violet colored abdomen 

 of the adult male. The female commonly lays her eggs on 

 mats of algse which float in the shallow water. While she 

 is ovipositing the male continues to clasp her body, holding 

 his wings folded and his own body poised stiffly, sticking 

 straight up into the air. Length of nymph, about one half inch. 



Enallagma. — This is a large genus of damselfiies whose 

 nymphs live in the tangled vegetation of small weedy ponds, 

 or slow-flowing streams, where they are among the most 

 numerous of predatory insects. Nymphs of the different 

 species are ver}" much alike (Fig. 169). All are slender 

 with the head nearly one-third wider than the rest of the body 

 and the gills variable in size and color pattern but not so 

 pointed as those of Ischnura. The labium is slender with a 

 prominent median lobe. Length of nymph, one half inch. 



Fig. 170. — Nymph and adult of Ischnura verticalis, 



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