Odonata Families:
Click on each to display information below .
Family Calopterygidae
Broad-Winged Damselflies
These damselflies are most often found near slow moving streams resting on overhanging grasses and sedges. They have green or blue iridescent bodies roughly 30-40 mm in length with a contrasting black pair of wings. Species of Calopterygidae may be identified by having a first antennae segment longer or equal in size to the remaining antennae. The larvae may be distinguished from those of dragonflies by three leaf-like gills at the end of the abdomen, and are often found burrowed in the substrate in still or slow moving water.
Family Coenagrionidae
Narrow-Winged Damselflies
Coenagrionids are part of the most diverse family of damselfly in the Upper Midwest; there are 96 species that belong to this family in North America. Damselflies in the family Coenagrionidae are commonly referred to as pond, or narrow-winged damselflies. They are found in a wide variety of habitats ranging from slow running streams to pond and lake margins. The body length of adult Coenagrionids ranges from 15-32 mm, and the wings are clear and colorless. The body of the adult is usually decorated with a black pattern against a green, blue, yellow, orange, or purple background. In some species the females have two color patterns (color morphs), one that resembles that of the male species, and another that is a brown and gray pattern that acts well as camouflage.
Family Lestidae
Spread-Winged Damselflies
These damselflies are most common in marshes, bogs, or slow-moving streams that are surrounded by ample vegetation. Damselflies in this family are commonly named spread-winged damselflies. The average body length varies between 22 and 38 mm. These species possess more ommatidae eye cells than any other family of Odonata except Aeshnidae. Consequently, they are wonderfully adapted for visual hunting. The larvae of the family Lestidae also possess unique behavioral adaptations that allow them to conserve energy based on the concentration of oxygen available for respiration. Larvae remain relatively inactive at night, when oxygen levels are low and unfavorable for active predation. This allows them to conserve energy for use during the day when oxygen levels are higher and larval respiration is more efficient. This adaptation may help the larvae to grow rapidly and emerge in early summer during favorable environmental conditions.
Family Aeshnidae
Darner dragonflies
These dragonflies are commonly named darner or hawker dragonflies. The fastest and the largest dragonflies in North America are found in this family. The common name “darner” refers to that fact that the adult female abdomen, that is used to cut into plant material to deposit eggs, resembles a sewing needle. The adults of this species of dragonflies are most frequently found along lake and pond edges, often clinging to aquatic vegetation. The average body length is 30-62 mm. The eggs of the adult Aeshnidae species are laid inside plant vegetation. And, unlike many other dragonfly insects, dragonfly larvae in this family stalk their prey instead of waiting for prey to come near. The well-adapted, large eyes that these species have make them ideal for using aggressive predatory techniques as both larva and adults.
Family Cordulegastridae
Spike-Tail Dragonflies
Species in this family are commonly named the spike-tail dragonflies. The larval form is large in comparison to other Odonata larvae; the average larval body length is between 30 and 45 mm. These larvae are usually found buried in the silt or sand at the bottom of a pond or slowly moving stream. The insects burry themselves by moving their legs with a side-ways kicking motion. When buried, only the eyes and the tip of the abdomen are above the substrate. The larva may lie buried under the silt for weeks until an unsuspecting prey moves near its hiding place. The larvae have a hairy appearance because of the many small setae, or hairs that cover the insects’ body. It is thought that these setae may assist in prey detection and camouflage as the hairs increase the number of sand and mud particles that will adhere to the larva’s body. Larvae generally emerge in June of each year, but any one insect could remain in the larval stage for two to three years before undergoing metamorphosis to become an adult. Adult females begin to lay their eggs one month after emergence in early July.
Family Gomphidae
Club-Tail Dragonflies
Species in this family are commonly referred to as club-tail dragonflies in reference to the enlarged area at the end of the abdomen in the adult. The larvae are generally 30-45 mm in length and the adult Gomphidae is 40-70 mm in length. The adult is usually green or yellow in color with black stripes, and the adults can be easily distinguished from adult dragonflies in other families by their small and widely spaced eyes. Similar to species in the family Cordulegastridae, larvae in the family Gomphidae also bury themselves in silt or sand at the bottom of lakes and ponds. While buried, the tip of the abdomen remains above the substrate so that the insect can continue to obtain dissolved oxygen from the water above the substrate. Interestingly, in most Gomphid species the larvae climb out of the water onto shore instead of up aquatic vegetation at the time of emergence.
Family Libellulidae
Skimmer Dragonflies
Species members of this family are categorized by many common names including, skimmer dragonflies, emerald dragonflies, green-eyed skimmers, and cruiser dragonflies. These dragonflies are often found in wetlands, ponds, and small lakes where there is still water. The adult skimmer dragonfly is commonly seen perched on exposed branches or logs. Body length within the family Libellulidae is variable; adult body length ranges from 30-100 mm, while the larval body length ranges from 18-42 mm. One defining characteristic of adult Libellulidae is that the body length is noticeably smaller than the wingspan. The wings are often colored or patterned, and the body is usually red, yellow, or blue in color. Species in this family tend to perch at rest from flight more often than other families of dragonflies. When Libellulidae perch they hold their wings horizontal and tilt their abdomen upward. The males are territorial, and some males will instigate fights with other males if their sovereignty is threatened. Libelludid larva are well camouflaged by coloration or by a layer of sediment.
Odonata Life stage history
Larval
Like most members of the subclass Insecta, the Odonata larval stage is completely aquatic. The larvae possess a unique large lower lip that covers the mouth parts and the majority of the insect’s head when viewed ventrally (from the belly-side). Odonata larvae pass through 10-15 instars, meaning that they will molt 10-15 times before emerging as a winged adult. The molts, or exuviae, from emerging larvae are often seen attached on the stems of grasses near the water’s edge. Respiration in Anisoptera or dragonfly larvae is primarily through rectum. Muscle contractions and relaxations in the rectum pump air into and out of the anus. The air pumping capabilities of the rectum also serve as an emergency avoidance mechanism. Air can be quickly forced out of the rectum to project the larva away from a potential danger. In Zygoptera larvae, or damselflies, oxygen is mainly obtained from diffusion through the skin and gills.
Adult
The adults in both suborders have two pairs of wings; in general, the dragonflies will hold their wings at rest horizontally, and the damselflies will fold their wings behind the body while at rest. The adult form is long and slender, and the body length of most adults is between 15 and 120mm. The adults of both suborders live out of the water, but Odonata adults hunt for water-dwelling prey and lay eggs on the surface of the water. Some dragonfly and damselfly adults also possess a unique ventilation behavior that includes thoracic and abdominal pumping. Thoracic pumping occurs when the muscles of the thorax contract in flight, consequently increasing and decreasing the size of the thoracic box and forcing air in and out of the thoracic air sacs. The second respiratory mechanism, abdominal pumping, involves the contraction and relaxation of the abdominal muscles. This muscle action forces air into and out of the abdominal air sacs.
Feeding habits
Both larvae and adults are predatory insects. Odonata larvae extend their unique large lower lip in front of the body to catch prey which may include small fish, tadpoles, or even other dragonfly or damselfly larva. Some species use a sit and wait ambush prey capture strategy, while others will actively stalk prey. The strategy used varies amongst prey species as well as prey and predator density. Adults feed primarily on terrestrial flying insects that they catch prey while in flight.
Ecological importance
Due to their low predatory position on the aquatic food chain, counts of Odonata populations are useful for determining the health of aquatic ecosystems. Changes in health of the aquatic ecosystems are more quickly identified by animals lower on the food chain than changes in populations of larger mammals or top predators. Some national parks in the United States are beginning to consider population counts of Odonata species when devising new management techiniques.
