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Orange Bluet



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Enallagma signatum

Hagen, 1861


Order Odonata
Suborder Zygoptera
Superfamily Coenagrionoidea
Family Coenagrionidae
Genus Enallagma
Species signatum (Hagen, 1861) [Agrion]


Identification

The face of the male is orange except for a narrow black stripe across the front. The top is black an orange occipital bar that is nearly confluent with two narrow postocular spots. The middorsal thoracic carina is black and a third as wide as the mesepisterna. The antehumeral stripe is orange and half the width of the middorsal stripe. The humeral stripe is black and subequal in width to the antehumeral stripe. The remainder of the thorax is orange. The legs are orange with the occasional black stripe on the femora and tibiae. The abdomen is orange dorsally and paler laterally. The dorsum of segments 1-2 are nearly all black. Segments 3-8 are black except for a pale basal ring that is generally lacking on 8. Segment 7 has a narrow apical ring. There is a pale basal ring on segment 9 and 10 is black dorsally. The cerci are subequal in length to segment 10. The pale paraprocts are half the length of the cerci. Teneral and young males are blue rather than orange. The female is paler in color, generally yellow-green. The head and thorax are similar to the male, but with the pale areas more extensive. The humeral stripe is generally narrower than the yellow antehumeral stripe. The pronotum has distinct pits on the anterior third of the middle lobe. The mesostigmal plates are nearly triangular with a prominent tubercle at the posteromedial corner. The pale colors of the abdomen are yellowish-green. Segments 1-8 are generally like the male. Segment 9 is black dorsally and segment 10 is generally pale.

Size

Total length: 28-37 mm; abdomen: 23-30 mm; hindwing: 15-21 mm.

Similar Species

Cherry (E. conciusum ) and Burgundy (E. dubium ) Bluets are both smaller and red not orange. Teneral Vesper Bluets (E. vesperum ) are similar, but the black humeral stripe is either lacking or narrowly reduced in that species. Our threadtail species (Family Protoneuridae ) are orange and are found along side Orange Bluet, but they will have much longer and thinner abdomens (twice as long as the wings).

Habitat

Various ponds and lakes as well as slow moving streams and rivers

Discussion

Found in a variety of habitats, Orange Bluet is unusual in that it is most active in the late afternoon. One study found it never appeared before 2:30 P.M. In this respect, it is similar to Vesper Bluet. Females stay some distance from the water and are often not encountered except in copula or tandem. Females are one of three forms. The first remains blue throughout life, one becomes green and the third becomes orange. Males are often seen hovering low to the water, occasionally perching on water lilies or other emergent vegetation. A study on the reproductive behavior of Orange Bluet found females will posture their unwillingness to mate. After mating, pairs will begin laying eggs in floating vegetation or debris, wi th the male often accompanying his partner underwater. Females will remain underwater, ovipositing in the traditional manner for up to 20 minutes at a time. References: Dunkle (1990), Lutz and Pittman (1970), Tennessen (1975).

Distribution

Eastern U.S. from Florida to Quebec, westward to South Dakota and south to Texas.