Although there is no specific information on this species, dragonflies in general use their wings and body coloring to communicate with each other. During mating, courtship, and recognition, dragonflies display brightly colored regions of their body (such as their eyes, legs, and wings) to create specific signals. They have acute vision: their compound eyes are one of the largest of all insects and contain the most ommatidia. Adults are able to see in basically all directions except for directly behind their heads since their bodies and wings block their vision. These compound eyes are able to detect not only color, but also UV light, plane of polarization of light, and movement (important for foraging while in flight).
Communication Channels: visual ; tactile ; acoustic
Other Communication Modes: pheromones
Perception Channels: visual ; ultraviolet; polarized light ; tactile ; chemical
Although Canada darners is not a threatened species, conservation for dragonflies are being put forth. Their economic and ecological importance have increased research within the Odonata order. Several methods have been suggested to protect dragonflies, such as establishing protected areas (National Parks, nature reserves, etc.), conserving their natural habitats, and regulating pollution and increasing legislation, and developing programs for public awareness and education of dragonflies.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Darners (Aeshnidae) lay eggs endophytically, meaning they are inserted eggs into plants (stems, etc.) at or under the water using their ovipositors. The eggs are long and clyindrical and are coated with a jelly-like substance that helps them attach to substrates. If environmental conditions are harsh, the eggs may undergo a state of dormancy, or diapause, until conditions become more suitable. Larvae are hatched from the eggs usually within one to three weeks and undergo several moltings. Dragonfly larvae lack caudal gills and are able to feed on a wide variety of food, including other insects, small aquatic animals (tadpoles), and other insect larvae. In general, dragonfly larval stages can last anywhere from six months to five years depending on the type of species, the water temperature and food supply. During the final larval stages, all the organs and other characteristics are developed to ensure success as a winged insect. Generally, dragonflies have three stages as adults: pre-reproductive, reproductive, and post-reproductive. During the pre-reproductive stage, the adult is called a teneral adult. It is still colorless, unhardened, and has weak flight. This phase usually lasts for approximately 24 hours after emerging from its larval stage. Once the wings have hardened, the newly molted adult will fly away from water to prevent being preyed upon. For a few days the immature adult will continue to develop gonads and respective gametes. Males develop faster and will go back to the water after maturity to guard and defend territory.
Development - Life Cycle: metamorphosis ; diapause
Although there is little specific information on Canada darners in particular, in general dragonflies cause a negative effect in pollination and seed dispersal. They prey on pollinators, such as bees (both wild colonies and solitary pollinators), which makes "queen rearing" almost impossible in regions of the south-eastern United States. They can also act as an intermediate host to a number of parasites that can cause diseases in both humans and birds. Several genera of trematodes can infect dragonflies that, when passed onto birds, directly causes abnormal egg production. Poultry, as an important food source to humans, are largely affected during spring and summer months by eating adult dragonflies or dragonfly larvae. Many humans can be directly infected by trematodes carried by dragonflies when they eat raw larvae (typically in cultures of south-east Asia). If the larvae is cooked before consumption, infection can be avoided.
Negative Impacts: injures humans (causes disease in humans ); crop pest; causes or carries domestic animal disease
Dragonflies and damselflies have been used in research to assess and monitor several areas of aquatic ecosystems, which include but are not limited to water quality, biodiversity, and testing ecological and evolutionary theories. Their sensitivity to global climate change aids in climate regulation as well. They have increasing significance as an important bioindicators of water flow regulation, purification, and waste treatment, all of which are factors that influence habitat health. Beneficial health services arise from the study of dragonflies in medical laboratory settings. These studies have helped illuminate metabolic diseases such as diabetes and obesity in humans and have furthered developed genetic studies. Pest regulation, specifically mosquito control, is another important factor that impacts humans.
Dragonflies, in general, have had significant cultural and provisioning importance in many areas across the world, especially in East Asia. In East Asia they are believed to possess medicinal properties and are used in traditional medicine. Although they are not a staple food, they are enjoyed as delicacies and side ingredients in several areas of Asia and Africa. Like butterflies, their ornamental value can be seen through cabinet displays in homes, museums, and other buildings. They have also developed spiritual values in many cultural societies including the Navajo Indians as a symbol of pure water, and Japanese warriors believe them to be a symbol of strength and beauty. Their aesthetic ideology also provides a rich environment that stimulated the creations of recreational parks and trails specifically for dragonflies that bring many tourists and much public appreciation for these insects.
Positive Impacts: food ; ecotourism ; source of medicine or drug ; research and education; controls pest population
Canada darners are not only predators and a food source for other animals, but they can also act as parasitic vectors both in their larval stage and adult stage. They can be infected by several species of flukes (Phaneropsolus bonnei and Prosthodendrium molenkampi) that can cause diseases in birds and humans. Besides internal parasites, adults can be hosts to water mites (Erythraeidae and Hydrachnidiae) and minute flies. In areas of still waters, such as ponds and lakes, water mites deposit their eggs onto the bodies of dragonflies. Minute flies can be found on the bases of dragonfly wings, where they securely attach themselves and drink blood from the wing.
Commensal/Parasitic Species:
Dragonfly larvae are skilled predators, able to stalk their prey and eat a variety of different foods. Darner (Aeshnidae) larvae eat snails (and other freshwater gastropods), a variety of flatworms, leeches, fish eggs, zooplankton (fish larvae), juvenile fish, amphibian larvae, and larvae of other insects. In order to capture their prey, dragonfly and damselfly (Odonata) larvae use their prehensile labium, also known as a "mask", that is unique to this order; it is formed from the fused second maxillae. While in rest the prehensile labium is folded underneath the head and thorax. This structure is highly specialized to capture prey and can be quickly protracted which is useful in capturing mobile prey and for ambush.
Adult darners capture and eat their prey while in flight. Flight patterns change as dragonflies stalk and capture prey in the air. They are able to dart sideways, upwards, and sometimes downward to pursue their prey. They use only their mouthparts to capture prey, but males will sometimes push the tips of their abdomens towards their mouth in an attempt to subdue and maneuver their catch. After catching their prey, some dragonflies return to the ground, especially when dealing with larger prey. When the prey is smaller and is caught in midair, dragonflies remain in flight while they eat. In general, dragonflies eat according to the abundance of food around them. They do not seem to have a specific diet, mostly eating whatever is most abundant and suitable in size within their habitat. It can be hard to determine what exactly constitutes their diet because adults masticate (chew) their food very thoroughly into a black paste which results in diet identification being difficult. Some examples of their diet include, but are not limited to, spiders, damselflies, butterflies, other dragonflies, and various other insects.
Animal Foods: amphibians; fish; eggs; insects; mollusks; zooplankton
Primary Diet: carnivore (Insectivore , Molluscivore )
Aeshna canadensis is native to a broad area in Canada and the United States, including the following states or provinces: Alberta, British Columbia, Manitoba, New Brunswick, Nova Scotia, Ontario, Quebec, Prince Edward Island, Saskatchewan, Labrador, Yukon Territory, California, Connecticut, Illinois, Indiana, Iowa, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, New Hampshire, New Jersey, New York, Ohio, Oregon, Pennsylvania, Rhode Island, Vermont, Washington, West Virginia, and Wisconsin.
Biogeographic Regions: nearctic (Native )
This species inhabits both terrestrial and freshwater environments, including bogs, beaver ponds, lakes and other freshwater areas with plentiful forest vegetation. They aggregate around wet areas that are shallow with floating vegetation and logs to breed and feed within forest limits (e.g. forest edges and small clearings). Most often they can be found flying or perched in fields, pastures, and clearings. In general, dragonflies are limited to live in areas that have relatively clean water. They are sensitive to water current strength and temperature. They are not limited to inhabit specific areas based on food availability.
Habitat Regions: terrestrial ; freshwater
Terrestrial Biomes: forest
Aquatic Biomes: lakes and ponds; rivers and streams
Wetlands: marsh ; swamp ; bog
Other Habitat Features: riparian
There is no specific information on the lifespan of Canada darners, but the life expectancy of adult dragonflies is usually dependent on environment and where in the world the species is located. Dragonfly adults in generally live a few months as adults. Most of the lifetime of dragonflies is lived in the larval stage.
Canada darners are characterized by blue and brown coloring, and males more brightly colored than females. Males can be identified by the presence of blue stripes on the top and sides of their brown thorax and a deep indentation on the front of their thorax. Their abdomens are also brown with blue markings. Females are duller with three possible color forms: blue, green, and yellow. Blue form females, though rare, can often be mistaken for males since their coloring and pattern are very similar. The green form females have green markings and usually have brown tipped wings. The intermediate and yellow forms are the most common. Females are marked with green lateral thoracic stripes, green dorsal abdominal spots, and blue lateral abdominal spots. As the temperature decreases, the color of this species can darken.
The larva of darners (Aeshnidae) are climbers or weed-dwellers, so they have long, smooth bodies that enable them to move easily through vegetation to stalk and capture their prey. Eggs are usually long and spindle-shaped with a moderately thick, homogeneous vitelline envelope, a many-layered endochorion, and an elastic exochorion which can be covered with many small pores or enveloped in a jelly-like substance.
Range length: 68 to 74 mm.
Sexual Dimorphism: sexes colored or patterned differently; male more colorful
Other Physical Features: ectothermic ; bilateral symmetry
On the ground, adult Canada darners can fall prey to ants and spiders. Birds and frogs are huge predators that hunt both adult and nymph forms of dragonflies. Cannibalism also occurs. Nymphs may also be eaten by fish and other, larger aquatic insects. Along with other dragonflies, Canada darners are adept in maneuvering in the air to escape predators such as birds by twisting and turning. Camouflage is another major mechanism through which dragonflies in general utilize to escape being eaten. Depending on their coloring they can blend in with surrounding foliage (grass, bushes, trees, etc.)
Known Predators:
Anti-predator Adaptations: cryptic
There is little specific information on the mating systems of Canada darners. In general most dragonflies have several mates for both females and males. Usually dragonflies are fiercely competitive for females and optimal egg-laying sites. Males usually come to breeding grounds earlier in the season and earlier in the day than females. They find and guard good breeding grounds and defend their territory from intruders or other males by flashing brightly colored parts of their bodies (wings, legs, etc.) to warn off intruders. As females start to enter the breeding grounds, males begin courtship rituals such as raising his abdomen to the female to identify himself. A female may accept or reject a male. Rejection is displayed by curving the abdomen downward. Once a pair has mated, males can guard the females in two different manners. They can either stay physically attached in tandem while the females lay her eggs, or the male will separate and perch nearby to chase away any intruders (male competitors or predators) as the female lays her eggs.
Mating System: polygynandrous (promiscuous)
Although there is no specific information on Canada darners, members of their genus (Aeshna) mate quickly and near the water. Males are typically found hovering over and patrolling water edges while the females keep to the forests, only coming near the water to mate and lay eggs. There is fierce competition for females and optimal egg-laying sites. Males guard breeding areas by flashing brightly colored parts of their bodies (wings, legs, etc.) to warn off intruders. Once a female enters the male territory, her thorax is grabbed by the male's legs. Before the actual mating begins, males will transfer their sperm from their testes (under-segment 2 and 3) to their hamulus (under-segment 9) by arching the abdomen until the bottom-sides of the organs make contact. The male then curves his abdomen in order to fit his apical claspers (anal appendages) behind the eyes of the female to deposit his sperm. This process is often described as a pair "in tandem". While in tandem, the male will attempt to remove any sperm ejected from previous males prior to releasing his own sperm to ensure that his will be the one to fertilize the eggs. He can do this with two methods. First, he can remove the sperm from previous matings using his spoon-shaped penis, or he can shove the sperm deep into the female organ so that they are inaccessible. After the transfer of sperm, the male will arch his abdomen downward while the female arches hers upward towards the male's hamulus, forming the wheel position or "in copula". Females deposit their fertilized eggs into a plant stalk right above the water by cutting into the stem using their ovipositors.
Breeding interval: Canada darners breed once yearly.
Key Reproductive Features: semelparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
Females lay fertilized eggs in the stem of a plant, where they create a nest-like cavity using their ovipositor. Little else is known about parental investment in Canada darners.
Aeshna canadensis, commonly known as the Canada darner, is a species of dragonfly in the family Aeshnidae. It is common throughout southern Canada and the northern United States.[2][3]
Adult Canada darners, similar to other members of the genus Aeshna, are relatively large, slender dragonflies, and are predominantly dark brown with paler blue or green markings.[4][5] Adults are 64 to 73 mm in total length.[5] The thorax has two vertical stripes on each side, the front with a prominent notch and an extension at the top.[5] The abdomen has spots on most segments.[5] The pale markings are usually blue in males and range from yellow-green to blue in females. The eyes are bluish in males and yellowish or bluish in females.[5] The pale markings may turn gray at colder temperatures.[5]
The green-striped darner is very similar, but is distinguished by minor differences in the shape of the markings and in typically having green thorax stripes.[5] The lake darner is also similar but is larger and has a distinct dark stripe across the face.[5]
The Canada darner was first scientifically described in 1908 by Canadian entomologist Edmund Murton Walker, in the same publication as the first descriptions of black-tipped darner, shadow darner, subarctic darner, and variable darner, .[6]
Canada darners are found from Newfoundland and New Jersey in the east to Yukon in the west.[5] Populations extend further south down the Appalachian mountains to West Virginia and south in mountain ranges to California and Montana.[5][7] There is an isolated population in Nebraska.[5]
Canada darners spend most of their lives as an aquatic nymph.[7] Larvae are typically found in lakes and ponds, especially bog ponds and beaver ponds.[5] Breeding ponds typically have abundant emergent vegetation.[5] An Ontario study found that the species was restricted to ponds with a pH of no more than 6.2.[8] One study found that larvae may spend either one or two winters underwater before emerging.[7]
Adult males fly slowly along the shores of breeding ponds, sometimes dropping to the surface to search for females.[5] Mating occurs in shrubs nearby.[5] Females lay eggs at water level, usually in marshy vegetation away from shore.[5] Breeding adults are most active in sunny weather.[4]
Away from breeding sites, adult Canada darners are often found with other darner species in feeding swarms in clearings and along roadways in early evening.[4][5] Adult Canada darners may be seen from June to October.[5]
Canada darners are often considered to be a common to abundant species where they are found.[4][8][9][7] Although the species has not generally been recognised as migratory, a study in Manitoba and Minnesota found that at least some populations of Canada darners undertake north-south migratory movements within their range.[7]
Aeshna canadensis, commonly known as the Canada darner, is a species of dragonfly in the family Aeshnidae. It is common throughout southern Canada and the northern United States.
