Anax junius

 
 
Common Name:
Green Darner, Common Green Darner
Odonata
Order:
Odonata
Suborder:
Anisoptera
Family:
Aeshnidae
Genus:
Anax
Species:
A. junius
The Name
Anax junius (Drury, 1773), The Green Darner or Common Green Darner, after its resemblance to a darning-needle, is a species of dragonfly in the family Aeshnidae. Common throughout North America, it ranges south to Panama and occurs in the Caribbean, Tahiti, and Asia from Japan to mainland China. It is the official insect for the state of Washington in the United States.

The Green Darner is one of the largest dragonflies existent: males grow to 76 mm (3.0 in) in length with a wingspan of up to 80 mm (3.1 in).

Females oviposit in aquatic vegetation, eggs laid beneath the water surface. larval are aquatic carnivores, feeding on insects, tadpoles and small fish. Adult darners catch insects on the wing, including ant royalty, moths, mosquitoes and flies.

 

The Characteristics
The Green Darner is one of the largest dragonflies, with male sizes ranging from 70-76 millimeters in length and 90-104 millimeters in expanse, and female sizes ranging from about 68-80 millimeters in length and 90-106 millimeters in expanse. Both male and female are characterized by green thoracic region and a reddish-brown coloration ventrally in the abdominal region, with the female having slightly lighter coloration. Both male and female members of this species show light blue abdominal coloration dorsally. larvals are fully aquatic, six-legged, with large lateral eyes, elongate wingpads, and underslung mouthparts. Maximum length of larvals 50-55mm.

The Green Darner prefers still or very slow-moving fresh water, with lots of aquatic vegetation, and can only flourish where there are no predatory fish.

Adult Darners catch and eat insects on the wing, including moths and mosquitos. Dragonflies are excellent aerial hunters, due to its tremendous flying speed (recorded at up to 18 mph) and incredible eyesight. They use their powerful jaws to tear apart and chew up their prey. Green Darner larvals are wholly carnivorous, usually eating aquatic insects, tadpoles, and very small fish. 
 
 

 

The Reproduction and Development
Reproduction usually occurs in the summer months of July and August. Due to the briefness of the adult darner's life cycle (perhaps only a few weeks), they are mainly concerned with reproduction. To prepare for copulation, the male loops his abdomen forward to transfer semen from his true genital opening to a receptacle located in his secondary genitilia. Now the male is ready to select a mate. Once he has done so, the male will fly up to the female and, using his genital claspers located at the tip of his abdomen, he will grab hold of her by the neck to ensure that she will not escape. The two will form what looks like a circle with their bodies as the female aligns her genitilia with the secondary genitilia of the male located at the base of his abdomen. The male will then insert his secondary sex organ into the female's vagina, packing down or removing the sperm of any previous mates. Only after this will the male deposit his own sperm into the female.

After copulation, the male will continue to hold onto the female's neck, probably for the rest of the day, in order to prevent any other males from mating with her, removing his sperm, and replacing it with their own. The male will fly around with the female while she lays her eggs, often guiding her to the most ideal spot for the eggs. Once a location has been selected, the female will insert her ovipositor, a knife-like egg-laying organ, into pieces of rotting wood or in the stems of growing plants at the edge of a pond. This egg-laying procedure is the only form of nurturing that the offspring will receive from their mother. Females always lay copious amounts of eggs in order to ensure that at least some will hatch and fully mature into adult dragonflies.

Green Darner eggs will hatch within about three weeks and small spider-like larvals will emerge.

In warm water regions, where food is plentiful, a larval may develop in as little as one summer, but as more often is the case, in cold water regions, where food is less plentiful, a larval may take as long as four years to fully develop into an adult darner. Some adults migrate south in winter, and return north to lay eggs the following spring.
 

 

The Distribution
The breeding range of Anax junius extends from the northernmost part of the United States (Alaska) and south to Panama; also occurs from Hawaii east to Nova Scotia; also occurs in West Indies and Tahiti. Known to occur in Asia from Kamchatka south to Japan and mainland China

 

The Protection Status
This species is fairly common and abundant throughout its range. The main threat to its persistence is destruction of the freshwater habitat it requires to breed.
 

References:
http://en.wikipedia.org/wiki/Green_Darner
http://animaldiversity.ummz.umich.edu/site/accounts/information/Anax_junius.html
The Species on Stamps
Tuvalu
2001.10.31
St. Vincent Grenadines
2002.02.01
Micronesia
2002.12.16
Canada
2006.03.08

 
 
 
 
 

 


With courteous to Mr. Richard Lewington for the Dragonfly Illustration
       
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