The order Odonata contains the dragonflies and damselflies and is one of the most popular insect groups. Odonates are popular with both the amateur and professional because they are large, colorful, easily observable and have exceptionally charismatic behaviors. In recent years dragonflies in particular have been popular with birders as many dragonflies rival birds in wingspan, color, gregariousness, and predictability. As a result of their popularity with the public, they have become the focus of many conservation efforts in North America, Europe, and Asia. To facilitate the discussion of North American odonates it is useful to use the names Zygoptera and Anisoptera when discussing differences between the damselflies and dragonflies, as there are no extant Anisozygoptera in North America.
Dragonflies make up the more specious of the two suborders and are much more easily observed than their dainty relatives, the damselflies. They have large eyes that take up nearly the entire head surface and when not contiguous are not as widely separated as within the damselflies. They also have a very robust body structure to support a massive musculature that propels their large, broad wings. Dragonflies are unmatched as fliers and have a very agile, deliberate flight. Males are often territorial, defending oviposition sites from other males.
There are six families of dragonflies found in Florida, each of which is easily identifiable. These insects are commonly found around ponds and open bodies of fresh water and large blacktop parking lots. There are a number of species that disperse away from water for a time before returning with a mate to breed and deposit eggs. Damselflies in North America and particularly in Florida they have similar characteristics, which are: eyes separated by more than the width of a single eye, abdomen much longer than wings, very slim body structure and a simple fluttering flight. Damselflies can often be quite spectacular in color. Away from the forest habitat the most commonly encountered families is Coenagrionidae, which can be observed just about anywhere along the edges of water systems. A less common family of damselflies is Lestidae. This group is readily identifiable in the field by their behavior of perching with their wings held open, a characteristic more common to dragonflies than damselflies.
Odonates are found on every continent except for Antarctica. Some species of dragonfly have vast distributions such as the blue-eyed darner which is found from coast to coast in North America, in addition to Central and South America. In contrast, many families of damselflies are narrowly restricted and several families have an extremely limited distribution.Florida is home to more than a 150 species of odonates belonging to three families of damselflies: Calopterygidae, Coenagionidae, and Lestidae and six families of dragonflies: Aeshnidae, Cordulegastridae, Corduliidae, Gomphidae, Libellulidae, and Petaluridae. They can be seen near any body of water or running stream, often sitting in sunspots breaking through the forest canopy along a river or pond, or patrolling the water's edge. Some species can be found in open fields far away from water while searching for prey or while migrating.
Eggs: Odonate eggs display a large array of shapes, from those that resemble tiny rice grains to minute mangos. The eggs can be seen in three ways: endophytic (within a plant), epiphytic (on the surface of the plant), and exophytic (on water or land, Corbet 1999). Generally, eggs are several times longer than wide while those laid epiphytically and exophytically are ellipsoidal to subspherical. Clutch sizes can be as large as 1500, with some females depositing several thousand eggs in a lifetime. Eggs hatch seven to eight days after oviposition but hatching can be postponed for up to 80 days and in one case 360 days.
Immature odonates (naiads): Immature odonates are referred to as larvae, nymphs, or naiads because odonates are aquatic hemimetabolous (lacking a pupal stage) insects as immatures. All naiads are voracious predators feeding on everything from small invertebrates such as mosquito larvae to smaller vertebrates such as fish and frogs. Naiads will molt nine to 17 times before becoming adults. The number of generations per year depends on the species of odonate. Species at higher altitudes or in dry environments usually have one generation per year while those in tropical habitats may undergo multiple generations per year depending on the availability of appropriate habitats. When naiads are ready they leave the water and will molt into adults. Much like a caterpillar emerging from a chrysalis, they need to pump up their wings and allow their bodies to harden before they can be effective fliers. A teneral (soft) dragonfly has glossy wings and the colors on the body are often pale. Several days after emerging and hardening completely, a dragonfly will have taken on the colors of an adult dragonfly.
Adults: Identifying males and females is not difficult. Males will have what appears to be a pouch on the second and third abdominal segments that contains secondary genitalia. The actual male genitalia are found on the last abdominal segments along with a grasping structure used to hold the female while mating. The male produces sperm at the tip of the abdomen and transfers this sperm to the secondary genitalia where the female will have access to it. Females do not have secondary genitalia or grasping structures at the end of the abdomen but instead have a single genital opening and a small ovipositor at the end of the abdomen that will be used to oviposit her eggs. Normally, the male dragonfly is more colorful while the female will be a dull brown or grey. When odonates mate they form what is called a "mating wheel." The wheel is formed when the male grasps the female behind the head and the female raises the tip of her abdomen forward to come in contact with the secondary genitalia of the male. Odonates can often be seen flying in tandem in this fashion.
Cache placed with permission from:
Sonya M. Thompson
Environmental Resources Project Supervisor
Miami-Dade Parks, Recreation and Open Spaces
Natural Areas Management
