|Variegated Meadowhawk – Sympetrum corruptum|
Insects | Odonata Index | Dragonflies | Damselflies | Odonata Main | Spiders
Live adult dragonfly photographed in the wild near the confluence of the Green and Colorado Rivers, Canyonlands National Park, Utah, USA. ~~ Canyonlands Map Here (.pdf)
The presence and abundance of dragonflies and damselflies may be taken as an indicator of ecosystem quality. Local populations can be strongly affected by any change in water flow, turbidity, or in aquatic or waterside vegetation. The greatest numbers of species are found at sites which offer a wide variety of microhabitats, prey, and clean water. Odonate nymphs are aquatic, and as such need unpolluted water.
Dragonfly mating logistics seem to me one of the more ridiculous contrivances in the animal kingdom. I followed these two green darners around for more than an hour; its quite comical to see them fly in tandem hooked together thus. They are quite good at it, however.
Dragonflies are unique in the insect world in that the male possess a set of secondary sexual organs on the 2nd abdominal segments as well as his primary sexual apparatus on the 9th segment at the end of his abdomen. Before mating can occur, the male dragonfly must charge his secondary copulatory apparatus with sperm from his primary copulatory apparatus. Mating commences with the male grasping the female with his abdominal claspers. The pair then assume the wheel position with the tip of the females abdomen and thus her sexual apparatus engaging the males secondary copulatory apparatus. The male first uses his penis to remove any sperm left by a previous male before inseminating her himself.
Copulation can take from several minutes to several hours depending on species. The male stays in tandem with the female in many species while she lays her eggs. In those species which lay endophytically some lay below the water line, and in some cases both the male and the female may become fully submerged. In other species the male stays close to the female guarding her while she lays, while in those strongly territorial species the male may be satisfied by continuing to expel other males from his territory allowing the female to lay within the territory.
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 360Â° field of vision, important for taking prey on the wing, as has done the female shown above.
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 damsels in their clutches.
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 Â¾ of an inch.
Dragonflies are the world's fastest insects and, although estimates of their speed vary wildly, most credible authorities say they are capable of reaching speeds of between 30 and 60 km/h (19 to 38 mph). A study showed that dragonflies can travel as much as 85 miles in one day.
1. Bruce Marlin, Bugguide.net, 'Variegated Meadohawk'
Order Odonata: dragonflies and damselflies date back 300 million years, to the Carboniferous Period of the Paleozoic Era. These colorful, enchanting insects are revered second only to the butterflies in the popular psyche. Explore detailed close-up photographs of live, adult dragonflies and damselflies photographed in the wild.
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