Find out more about our Species at Risk

Blue Dasher Dragonfly

Species: Blue Dasher – Pachydiplax longipennis
B.C. Status: Blue
COSEWIC Status: Special Concern

Key Information:

These vibrant dragonflies are one of a kind – the only member of its genus and the largest member of the skimmer family. Found living in and around still water, they are natural residents to wetlands and can be spotted flying around lakes, marshes, and bogs.

A dragonfly’s life is a process of metamorphosis. Females lay their eggs on plant matter on the surface of the water; and within 35 seconds they can lay up to 700 eggs! Once hatched, they begin life underwater as a nymph feeding on insects, invertebrates, small fish, and tadpoles. Themselves, they are also prey to fish.

At this stage, they are highly tolerant of wetlands with poor water quality and low dissolved oxygen levels. This makes them perfect predators of mosquito larvae, which also live in still or stagnant water.

Once matured and when the weather is right, they complete metamorphosis by emerging from their exoskeleton. Out of the water and up to the skies they go! They live the remainder of their life as winged-adults – ready to mate, reproduce, and eat flying insects.

Blue dashers are very aggressive predators and will eat hundreds of flying insects a day – which is up to ten percent of their body weight! They will defend their food sites for several days and then move on to another area of the water body. Males are often seen near water edges, creating their territory, whereas the females are seen around the vegetation. The only time the female blue dasher will approach the water is to lay her eggs; which happens in a matter of seconds.

The mating and courtship process between dragonflies is quite unique – you can watch in the video below in the Useful Links. They mate in the air, and when perched, they both close their wings and raise their abdomen. If you see this process, you may be a witness of the magic of life – which can be as quick as 2 minutes! Males will continue to be on guard throughout the fertilization and egg-laying process to prevent other males from attacking her and her eggs.

Although they are tolerant of poor water quality, they are under threat from both habitat loss and pollution. The destruction of wetlands for development, water diversion, and pollution/pesticide input into water bodies are threatening blue dasher populations; and many other species.

Identification – what to look for:

Adult:

Males:

  • Blue body with a white face
  • Blueish/amber eyes
  • Black tip to the abdomen
  • Black and yellow striped thorax (head)
  • 28mm to 45mm in length
  • Develop sky blue abdomen when they reach maturity

Females:

  • Dark bodies with yellow stripes downside
  • Amber/blueish eyes, more amber than the males
  • Once mature, they will turn blue but less vibrant than the males

Blue dasher larvae/nymph.

Where they are found:

  • They are common across all of North America, even into the Bahamas!
  • Summer species, so mostly spotted in the summertime
  • Live around and in still water bodies including wetlands, lakes and ponds.

Source: https://ibis.geog.ubc.ca/biodiversity/factsheets/pdf/Pachydiplax_longipennis.pdf

Useful links:

Article & Video: Baby Dragonfly’s Eating
Video: Blue Dasher Dragonfly in Flight
Video: How Dragonflies See the World
Video: Blue Dasher Dragonfly
Video: Dragonfly Laying Eggs
Info on Blue Dasher Dragonfly (pdf): BC’s Coast Region: Species & Ecosystems of Conservation Concern (Blue Dasher)

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Friends of Cortes Island Society (FOCI) is a charitable organization that has been active for over 25 years. Our organization exists to monitor and preserve the health of local ecosystems, and to provide educational programs that foster a greater understanding of the natural environment. Through all of our projects, we work to promote environmental integrity through community responsibility.

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