137 

 Smith and Pritchard: Odonota 



Naiads 



1. Middle lobe of labium cleft only to base of lateral 



lobes Hetaerina 



— Middle lobe of labium cleft far below base of lateral 

 lobes (figs. 4: 14d, 4:59A) AgHon 



Genus Agrion Fabricius, 1775 



The members of this genus are among our largest 

 damselflies. They are easily recognized by the wings 

 conspicuously marked with black or entirely black, 

 and by the metallic green body (fig. 4:59). The young 

 adults fly near bushes in the sunlight or rest on the 

 foliage; the older adults fly along the banks of small 

 'streams, with a dancing flight much like that of satyrid 

 butterflies. Where there are alternate rapids and 

 smooth stretches, they tend to congregate in the 

 rapids. Walker (1953) describes the mating habits as 

 follows: "We observed a male hovering before a 

 female, which was resting on foliage over a stream. 

 The four wings were spread apart like a cross and 

 vibrating rapidly. The male was within a few inches 

 of the female and, in less than a minute, the male 

 seized the female per collum and copulation ensued. 

 The pair remained on the leaf, the abdomen of the 

 female bending downward, but about half a minute 

 passed before the female finally bent the abdomen 

 forward to engage the genitalia of the male." 



Oviposition takes place without the accompaniment 

 of the male; however, the male may be close at hand 

 to ward off other males. The eggs are deposited in 

 almost any kind of plant tissue just beneath the 

 surface of the water. 



The long-legged, awkward naiads cling to roots 

 and stems in the current of medium-sized streams. 

 Agrion aequabile occurs in slightly larger streams 

 than does A. maculatum. 



Key to California Species 

 Males 



Wings entirely blackish (eastern U.S. and Canada; 



Nevada and California in the West) 



maculatum Beauvais 1805 



Wings with only distal part blackish (Washington to 



California) (fig. 4:59) 



aequabile calif ornicum Kennedy 1917 



Females 



Occiput with a prominent tubercle on each side; ptero- 



stigma with many cross veins maculatum 



Occiput without a prominent tubercle on each side; 

 pterostigma without cross veins except near ends . . . 

 aequabile calif ornicum 



b 



Fig. 4:60. Dorsal view of male abdominal appendages of 

 Hetaerina. a. vulnerata; b, americana (Ce leste Green). 



denus Hetaerina Hagen, 1854 



These are beautiful, slender, bronzy-brown damselflies 

 (fig. 4:61a). The males are conspicuously marked 

 with a ruby or carmine basal wing spot, but in the 

 females this spot is reddish or amber. The genus is 

 most abundant in the tropics, but is represented in 

 the United States by four species. Only the widespread 

 Hetaerina americana is recorded from California, but 

 H. vulnerata is also included in the key as it is likely 

 to occur in southern California. 



The adults frequent the edges of slowly but notice- 

 ably moving streams where the banks are overhung 

 with willows or other vegetation. They also flit low 

 over the rapids but do not fly far from water. The 

 females rest at the water's edge on logs or other 

 partly submerged objects and oviposit by thrusting 

 the abdomen beneath the water and inserting the 

 eggs into soft tissue. 



The naiads cling to trash, plants, and rocks at the 

 edge of the current of slow streams. Transformation 

 takes place a few inches above the surface of the 

 water. The naiad of Hetaerina vulnerata is unknown. 



Key to Species 



Ma les 



1. Dorsal abdominal appendages (as seen dorsally) with 

 a large, bilobulate expansion inside (fig. 4:606) (south- 

 ern Quebec and Ontario south to Florida, California, 



and Guatemala) americana (Fabricius) 1798 



— Dorsal abdominal appendages (as seen dorsally) with 

 an entire and slight expansion inside (fig. 4:60a) 



(Arizona and Utah to Colombia and Brazil) 



vulnerata Hagen 1853 



Naiads 



1. Antenna with proximal segment usually shorter than 



head maculatum 



— Antenna with proximal segment usually longer than 

 head (fig. 4:59/) aequabile 



Fema les 



1. Mesothorax with middorsal stripes almost as wide as 



the dorsum americana 



— Mesothorax with middorsal stripes about one-half as 

 wide as the dorsum, at least at anterior end . . vulnerata 



