 | Green Darner Dragonfly - Anax junius (Drury, 1773) Male & female specimens, mating wheel Live adult dragonflies photographed at DuPage County, Illinois, USA. Odonata Main | Odonata Index | Insects & Spiders | Spiders Index | Beetles Index | Butterfly Pictures |
Green darner dragonfly mating wheel; male is on the right.
| Dragonfly sex involves one very unusual step: before literally hooking up, the male must transfer sperm from his sperm-producing genitals (located in segment 9, at the tip of his abdomen) to the accessory genitals located on segments 2 and 3, underneath his abdomen. These include a sperm reservoir and a penis. Male dragonflies accomplish this transfer solo, before they attempt to copulate. This type of sperm transfer is unique to the Odonates among insects, although it is common in spiders. The female pictured above has her genitals (also located in segment 9 at the tip of her abdomen) clasped against the male's penis and sperm reservoir. The male holds the female behind the head with his 3 claspers, and she holds onto his abdomen with her middle pair of legs. They are able to fly while united thus, albeit slowly and clumsily, with the male towing the female. I followed these two around for about 10 minutes, until they'd had enough of me and flew off across the river. After mating, the male green darner will tow the female around and over water, where she will insert her eggs into the stems of water plants. Flying in tandem, the male can guard his mate from sexual assaults by other males. This practice is known as contact guarding, and is a common among damselflies as well. [1] |
Dragonfly docking apparatus - male claspers latch onto female's head
Identification: This widespread species is one of the most commonly seen, most often in flight. These large dragonflies are some of the strongest flyers around and can be seen patrolling high above grassy fields in search of prey. The face is pale green with a distinct black spot on the top of the frons bordered anteriorly by a blue semicircle. The thorax is green with brown only lightly represented on the lateral sutures. The wings are clear with a yellow costa. The abdomen is mostly blue, with green on segment 1 in males and greenish-brown or reddish-brown throughout in females. The brown superior caudal appendages in the male are long, about the length of segments 9-10 combined. Habitat: Near ponds and slow streams. Adults hunt while airborne over sunny fields and meadows, preying on midges, mosquitoes, Caddisflies and other flying insects. Life Cycle: Female inserts eggs singly into slits cut in stem of submerged plants. Naiads feed on tadpoles, small fish, and aquatic insects. When fully grown, naiads crawl from the water to transform into adults. The green darner is commonly known as the "Darning Needle" or "Snake Doctor." |
Dragonflies have excellent eyesight. Their compound eyes have up to 30,000 facets, each of which is a separate light-sensing organ or ommatidium, arranged to give nearly a 360° field of vision. Odonates are completely harmless - they do not sting or bite. Indeed, they are beneficial in the same respect spiders and other predators are beneficial - they keep the burgeoning insect population in check. Many of these species prey on each other; I often see dragonflies with damselflies in their clutches. Dragonflies are among the most ancient of living creatures. Fossil records, clearly recognizable as the ancestors of our present day odonates, go back to Carboniferous times which means that the insects were flying more than 300 million years ago, predating dinosaurs by over 100 million years and birds by some 150 million. Much larger dragonfly species existed in the distant past than occur on earth today. The largest, found as a fossil, is an extinct Protodonata named Meganeura monyi from the Permian period, with a wingspan of 70-75 cm (27.5-29.5 in). This compares to 19 cm (7.5 in) for the largest modern species of odonates, the Hawaiian endemic dragonfly, Anax strenuus. The smallest modern species recorded is the libellulid dragonfly, Nannophya pygmaea from east Asia with a wingspan of only 20 mm, or about ¾ of an inch. |
| References 1. Berger, Cynthia, and Amelia Hansen, "Dragonflies" Stackpole Books, 2004. |
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