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Great Spreadwing



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Archilestes grandis

Rambur, 1942


Order Odonata
Suborder Zygoptera
Superfamily Lestoidea
Family Lestidae
Genus Archilestes
Species grandis (Rambur, 1942) [Lestes]


Identification

Great Spreadwing is found commonly in the Texan biotic province westward. It is the largest damselfly in the United States and can be readily identified in the field based on its large size, spreadwing perching behavior and distinct bright yellow thoracic stripes. The mesepisternum is a complete dark, metallic green stripe no more than half the sclerite width. This stripe is generally not contiguous with the middorsal carina; though it is occasionally narrowed towards the middle. The mesepimeron is variable with a metallic green or black stripe. This stripe may extend the full-length or slightly more than 1/2 the width of the sclerite. The remainder of the pterothorax is yellow, resulting in two broad, pale stripes. The wings are either clear or smoky, becoming darker at tips. The first 1/3 to 1/2 of the abdomen is dark metallic green dorsally, becoming yellow or tan ventrolaterally. This pattern becomes obscured with age. There is a narrow, dark, middorsal stripe and black apical ventrolateral carinae on segment 9. Segment 10 has a proximally directed dark median triangle on its dorsum. Mature males develop a white pruinosity laterally and basally on segments 1 and 2, all of segments 9 and 10, and on the sterna of segments 7 and 8. Females are more robust than males. The general coloration is similar, but with the head paler. The dark mesepisternum and mesepimeron stripes are often narrower and sometimes nearly lacking. The proximal abdominal segments are pale bluish. Segment 10 is tan to nearly black. The basal plate of the ovipositor is truncated posterolaterally. Margins of the valves are strongly and coarsely toothed.

Size

Total length: 50-62 mm; abdomen: 38-47; hindwing: 31-39 mm.

Similar Species

Pond spreadwings (Lestes ) are smaller with the length of the hindwing less than 30 mm. No other damselfly in our region approaches the size of Great Spreadwing.

Habitat

Small permanent ponds or streams with slow or moderate flow

Discussion

This species was known only from the southwest United States up until the 1920's, but it has since undergone a dramatic range expansion northward. It now occurs as far northeast as western New England. One study showed that that neither males nor females exhibited any type of courtship behavior, and unreceptive females showed no refusal signs, but rather were simply not at the water or escaped by rapid flight when unreceptive. No pairs were observed ovipositing from beginning to end, but the longest observed egg-laying time was 109 min.

Distribution

South Carolina north to Vermont west to California and south through Central America to Colombia and Venezuela