The Clark Gardens Blog

by Jeanette Henderson

Dazzling, glittering, jeweled acrobats and the most agile of all flying insects are the Dragonflies and Damselflies that make up the insects belonging to the order Odonata called Odanates. Dragonflies belong to the suborder called Anlsoptera. Damselflies belong to the suborder called Zygoptera. There are about 5,500 species found worldwide, except in Antarctica. About 433 species are found in North America. Only a few in the Darner and Skimmer families are migratory. The best time to find these beautiful insects are usually on warm, sunny days about 65° or more from March to September around areas of water, grassy meadows, or wooded natural habitat areas. There is a continual turnover of "emergence" that varies through this time. Odanates live as nymphs underwater about 11 months and about 1 month after "emergence" as flying adults. The anatomy of the adult Odonate is head, thorax (3 segments, each with a pair of legs) and the abdomen (the tail) with 10 segments.

Some differences between dragonflies and damselflies are: Dragonflies are larger, they perch with wings open laid flat, eyes large and close together, they are fast fliers and their hind wings are broader than their forewings. Damselflies are small, they perch with wings folded together above their back, their eyes are separated on the side of their head, they fly slow and easily, and both sets of wings are the same size.

Dragonflies have amazing compound eyes and flexible aerodynamic wings that make them excellent predators. They rely on sight only to detect their prey. One of their main prey is mosquitoes. They feed in flight on live insects. Wings are light-weight, stiff and flexible with a network of complex veins. Each wing can flap independently, called asymmetrical flying. The U.S. Military and NASA have studied them in hopes of developing aircraft with similar abilities. These aerial acrobats can fly up to 35 miles per hour, lift twice their bodyweight, take off backward, launch vertically, hover motionless, execute unbanked turns, make a series of zig-zag swirling maneuvers and stop instantly.

Dragonflies have two large eyes and three small eyes called ocelli. The two large eye wrap around the head, allowing them to see in a nearly 360 direction. Each eye is composed of 10-30 thousand facets called ommatida, each facing a slightly different direction, seeing a slightly separate image, highly sensitive to detecting movement. They can see in the ultraviolet and the plane of polarization.

Life stages are: egg, nymph (larva), adult. Eggs are laid by the female on water, plants, or in soft sediments. Eggs hatch in a few days to 1 week into crawling insects called nymphs that spend their lives underwater, breathing through gills, molting repeatedly, eating mosquito larva, water fleas, tadpoles, small fish, etc. After about 11 months the nymph goes through a process that takes about an hour, a magical metamorphosis called "emergence." It emerges from the water and attaches itself to a surface and pushes out of its shell to become a winged, air-breathing adult. The first stage of the adult is called a teneral. For one to two days the Dragonfly is delicate as its body hardens and gains strength. The next stage is a juvenile. For one to two weeks they fly to foliage or grassy areas to feed, fly, sun and develop into mature adults. Then, they return to the water areas to mate. Males clasp the females behind the head, leading them in "tandem flight." Then, the female grabs the male around the tip of his abdomen with her six legs, bending her abdomen around, pressing the tip of her genital opening seg 8 to the male’s accessory organ seg 2 to take sperm. This is called the copulation wheel. The pair are in a heart-shaped circle. This position can last from a few minutes to a few hours. The female is ready to lay eggs immediately after mating. Males may guard their egg-laying mates. Some lead the females in tandem position over water to lay eggs.

Odanates play a major beneficial role as predators of mosquitoes and other biting insects. The larva also form an important link in food chains for fish and other aquatic vertebrates. Odonate numbers are declining and may be at risk of extinction. The single most important factor in the conservation of this species is the protection of land and aquatic habitats. The creation of new habitats, especially ponds, can be beneficial.
The British Dragonfly Society has published two pamphlets: "Dig a Pond for Dragonflies" and "Managing habitats for Dragonflies." www.dragonflysoc.org.uk

Since a young girl I have been fascinated by these beautiful insects and all creatures and creation. I hope to inspire a respect and companion for these wonderful gifts around us to preserve them and our natural habitat.