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Aeshna canadensis

What do they look like?

Canada darners are dragonflies that are mostly blue and brown. Males are brighter than females, and are brown with have blue stripes on the top and sides of their front of their bodies, and blue markings on the back halves of their bodies. Females are not as brightly colored. They usually have green or yellow markings, and occasionally blue ones. Canada darners can get darker in color as it gets colder. Their larvae have long, smooth bodies that move quickly through plants and help them catch prey. Their eggs are long and widest in the middle, and look like they are covered in jelly. (Corbet, 1999; Dunkle, 2000; Needham and Westfall, 1955; Nikula, et al., 2002; Silsby, 2001)

  • Sexual Dimorphism
  • sexes colored or patterned differently
  • male more colorful
  • Range length
    68 to 74 mm
    2.68 to 2.91 in

Where do they live?

Canada darners live all over Canada and the United States. They live in most of the provinces of Canada from the Yukon Territory to Prince Edward Island. In the United States, they are found from California to Maine and south to Nebraska and West Virginia. ("IUCN Red List of Threatened Species", 2011)

What kind of habitat do they need?

Canada darners live both on land and in the water. They live in wetland bogs, ponds made by beaver dams, lakes, and other places that have both freshwater and forests. They group together around shallow, wet areas with floating plants and logs that they use to feed and reproduce. They often live at the edges of forests or small clearings. Canada darners are usually flying or perched in fields, pastures, and clearings. In general, dragonflies are only found in places where the water is pretty clear. They are sensitive to the strength and temperature of the water. ("IUCN Red List of Threatened Species", 2011; Nikula, et al., 2002; USDA WRP, 2010)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

How do they grow?

Darners lay eggs by inserting them into the stems of plants or under the water. The jelly surrounding the eggs helps them stick on the plants or on the bottom. The eggs don't hatch right away if the conditions aren't right. Usually, the eggs take 1 to 3 weeks to hatch. Dragonfly larvae can eat a different kinds of foods like other insects or their larvae and tadpoles. They are larvae for 6 months to 5 years. The amount of time depends on the kind of dragonfly, the water temperature, and the food available. For the first 24 hours after they turn into adults, they are soft, colorless, and weak while flying. Males develop faster than females. After males mature, they return to the water to defend their territory. (Corbet, 1999; Silsby, 2001)

How do they reproduce?

Canada darners probably have similar mating systems to other dragonflies. Dragonflies compete intensely for females and for places to lay their eggs. Males get to breeding grounds before females do, and guard their territory by flashing brightly colored body parts. Males court females by raising the back part of their body, which is called their abdomen. Females accept or reject them by curving their abdomen down. Males guard their mates by staying attached to them or by chasing away competitors while females lay their eggs. Males and females have more than one mate. (Corbet, 1999; Mead, 2003; Silsby, 2001)

Canada darners probably mate in a very similar way to their closest relatives. Males usually stay around the water. Females stay in the forest, and come to the water only to mate and lay eggs. Males compete for females and places to lay eggs. They guard their spots by flashing brightly colored parts of their bodies like their wings and legs. Females lay their eggs in the stem of a plant just above the water. (Mead, 2003; Nikula, et al., 2002; Silsby, 2001)

  • How often does reproduction occur?
    Canada darners breed once yearly.

Scientists don't know much about parental investment in Canada darners. Females cut off the stem of a plant to make a place to lay their eggs.

How long do they live?

Scientists don't know the lifespan of Canada darners, but most dragonflies live just a few months as adults. They are larvae for most of the time they're alive. (Silsby, 2001)

How do they behave?

Canada darners are active during the daytime. They are usually found feeding in forests or swamps. They sometimes group together in large swarms to feed in fields or clearings. Males usually guard territories along or near the edge of the water. Females spend most of their time in the forests, and come out of the water to mate and lay eggs. (Dunkle, 2000; Nikula, et al., 2002; Silsby, 2001)

How do they communicate with each other?

Canada darners probably communicate in a very similar way to other dragonflies. They show off brightly colored parts of their bodies like their eyes, legs, and wings, to make different signals. They have the biggest eyes of all insects, and they can see color, ultraviolet light, and movement. Adults can see in almost every direction except directly behind their heads where their bodies and wings get in the way. (Corbet, 1999; Silsby, 2001)

What do they eat?

Dragonfly larvae are skilled predators that stalk their prey and eat a variety of different foods. Darner larvae eat snails, many kinds of flatworms, leeches, fish eggs, zooplankton and fish larvae, juvenile fish, amphibian larvae, and larvae of other insects. Dragonfly and damselfly larvae use a specialized organ called a prehensile labium that they stick out to catch their prey, and keep folded under their head and the front of their body during the rest of the time. This adaptation helps them catch prey in flight as well as to ambush them. (Brues, 1946; Corbet, 1999; Silsby, 2001)

Adult darners stalk, capture, and eat their prey while in flight. While chasing prey, they can dart sideways, upwards, and sometimes downwards. They capture prey using just their mouths, then return to the ground to eat if the prey is large. Dragonflies generally eat food that is abundant around them. Sometimes it's difficult for scientists to figure out what they eat because they chew their food so much. Darners eat spiders, damselflies, butterflies, other dragonflies, and also other insects. (Brues, 1946; Corbet, 1999; Silsby, 2001)

  • Animal Foods
  • amphibians
  • fish
  • eggs
  • insects
  • mollusks
  • zooplankton

What eats them and how do they avoid being eaten?

On the ground, Canada darners are eaten by ants and spiders. Birds and frogs often eat adult and young dragonflies. Sometimes they eat each other, too. Young Canada darners can also be eaten by fish and other large insects living in the water. Like other dragonflies, Canada darners can move quickly through the air, twisting and turning to get away form predators. They also camouflage themselves, blending in with the grasses, leaves, and trees around them. (Corbet, 1999; Silsby, 2001; Walker, 1953)

  • These animal colors help protect them
  • cryptic

What roles do they have in the ecosystem?

Canada darners are predators and a food source for other animals. They also get parasites as larvae and as adults. They get infected by different kinds of flatworms (called Phaneropsolus bonnei and Prosthodendrium molenkampi) that can cause diseases in birds and humans. Adults can also get water mites (called Erythraeidae and Hydrachnidiae) and minute flies on the outside of their bodies. In still waters like ponds and lakes, water mites lay their eggs in bodies of dragonflies. Minute flies live on their wings, where they attach themselves and drink blood from the wings. (Corbet, 1999; Córdoba-Aguilar, 2008; Walker, 1953)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host
  • flukes (Phaneropsolus bonnei)
  • flukes (Prosthodendrium molenkampi)
  • water mites (Erythraeidae)
  • water mites (Hydrachnidiae)

Do they cause problems?

Dragonflies in general usually have negative impacts on pollinating and dispersing seeds among plants. They eat insects that pollinate plants like bees. They get infected with parasites that can be carried to humans and birds. This includes parasites that affect eggs of chickens and other poultry raised by humans. Humans can then get infected with the worms carried by dragonflies if they eat raw larvae. (Córdoba-Aguilar, 2008)

How do they interact with us?

Dragonflies and damselflies are used by researchers to check the health of water ecosystems, because they are sensitive to changes in their environment. They are used by medical researchers who study diabetes, obesity, and genetics in humans. They also help control the number of mosquitoes. (Córdoba-Aguilar, 2008; Moore, 1997)

Dragonflies have special cultural meaning or are eaten in some parts of the world. In East Asia, they are used in traditional medicine. In Asia and Africa, they are eaten as a delicacy. They are used as decorations in many homes and museums. Navajo Indians consider them a symbol of pure water, and Japanese warriors believe they are a symbol of strength and beauty. Because humans enjoy looking at them, some recreational parks and trails have been created especially for dragonflies. (Córdoba-Aguilar, 2008; Moore, 1997)

Are they endangered?

Canada darners are not threatened, but there are efforts to conserve them. There is a lot of research on their relatives, because they are very important to economy and ecology. Researchers suggest protected areas, habitat protection, reducing pollution, and public education as ways to make sure they don't become threatened or endangered. ("IUCN Red List of Threatened Species", 2011; USDA WRP, 2010)

Contributors

Esther Yoon (author), University of Michigan-Ann Arbor, Renee Mulcrone (editor), Special Projects, Catherine Kent (editor), Special Projects.

References

Biodiversity Institute of Ontario. 2012. "BOLD Systems - Taxonomy Browser" (On-line). Aeshna canadensis {species}. Accessed July 30, 2012 at http://www.boldsystems.org/views/taxbrowser.php?taxid=94733.

2008. "Catalogue of Life: 2011 Annual Checklist" (On-line). Accessed July 30, 2012 at http://www.catalogueoflife.org/annual-checklist/2011/details/database/id/20.

Paul D. Pratt. 2002. "Darners of SW Ontario" (On-line). Accessed July 30, 2012 at http://www.netcore.ca/~prairie/aeshna.html.

International Union for Conservation of Nature and Natural Resources. 2011. "IUCN Red List of Threatened Species" (On-line). Aeshna canadensis. Accessed July 30, 2012 at http://www.iucnredlist.org/apps/redlist/details/165074/0.

NatureServe. 2011. "NatureServe Explorer" (On-line). Aeshna canadensis - Walker, 1908. Accessed July 30, 2012 at http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Aeshna+canadensis.

Brues, C. 1946. Insect Dietary: an Account of the Food Habits of Insects. Cambridge, Mass.: Harvard University Press.

Corbet, P. 1999. Dragonflies: Behavior and ecology of Odonata. Ithaca, NY: Cornell University Press.

Czaplak, D. 1997. "Aeshna" (On-line). Accessed July 30, 2012 at http://odolep.com/d_aeshnidae/aeshna_append.jpg.

Córdoba-Aguilar, A. 2008. Dragonflies and damselflies : model organisms for ecological and evolutionary research. Oxford: Oxford University.

Dunkle, S. 2000. Dragonflies through binoculars : a field guide to dragonflies of North America. Oxford: Oxford University Press. Accessed July 30, 2012 at http://books.google.com/books?id=MKUmCxZjOCAC&printsec=frontcover&source=gbs_ViewAPI#v=snippet&q=Aeshna%20canadensis&f=false.

Folini, F. 2007. "CalPhotos" (On-line image). Aeshna canadensis. Accessed July 30, 2012 at http://calphotos.berkeley.edu/imgs/512x768/0000_0000/0907/0409.jpeg.

Mead, K. 2003. Dragonflies of the North Woods. Duluth, MN: Kollath-Stensaas Publishing.

Moore, N. 1997. Dragonflies: Status Survey And Conservation Action Plan. International Symposia of Odonatology: 5.

Needham, J., M. Westfall. 1955. A manual of the dragonflies of North America (Anisoptera), including the Greater Antilles and the provinces of the Mexican border. Berkeley: University of California Press.

Nikula, B., J. Sones, L. Stokes, D. Stokes. 2002. Stokes Beginner's Guide to Dragonflies And Damselflies. Boston: Little, Brown.

Paulson, D. 2011. Dragonflies And Damselflies Of The East. Princeton: Princeton University Press.

Pratt, P. 2010. "Canada darner photos" (On-line). Accessed July 30, 2012 at http://www.netcore.ca/~prairie/acana.html.

Silsby, J. 2001. Dragonflies of the World. Washington, DC: Smithsonian Institution Press.

USDA WRP, 2010. "WRP Easement Management Species of Greatest Conservation Need (Odonatas)" (On-line). http://news-source.nrcs.usda.gov/Search/search.asp?site=IA&ct=ALL&qu=WRP+Easement+Management+Species+of+Greatest+Conservation+Need+%28Odonatas%29&Go.x=0&Go.y=0&Go=Search. Accessed July 30, 2012 at http://www.ia.nrcs.usda.gov/technical/EasementTools/WRP%20Grassland%20-%20Wetland%20Odonatas%20GCN%20table.pdf.

USGS, 2006. "Dragonflies and Damselflies (Odonata) of the United States" (On-line). Accessed July 30, 2012 at http://www.npwrc.usgs.gov/resource/distr/insects/dfly/usa/131.htm.

Walker, E. 1953. The Odonata of Canada and Alaska. Toronto: University of Toronto Press.

 
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Yoon, E. 2012. "Aeshna canadensis" (On-line), Animal Diversity Web. Accessed December 19, 2014 at http://www.biokids.umich.edu/accounts/Aeshna_canadensis/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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