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Dragonflies and Damselflies

Dragonflies (and damselflies)

Text & photos ©Rand Rudland

 

There are about 5000 species of Odonata in the world today, of which the Sunshine Coast harbours only 48, or about 1%, but this local number is slowly growing over the years as more observers are spending time in the field. Odonata is an order of insects that is characterized by a 1 – 6 years, free-swimming, predatorial larval stage with a trap-like lower mandible, hence the “odon” in the name, referencing teeth. What we see out of the water, however, is the short-lived aerial predator stage which lives for only weeks or months. 

So how do we know if we are seeing a dragonfly, a damselfly, or some other flying insect? It’s actually not that complicated. If your insect has mostly clear, veined wings, a long thin abdomen, and huge eyes in relation to head size, you’ve likely got an odonate. The next question then becomes, is this a dragonfly or a damselfly? For this answer you look at the position and shape of the wings and the size and location of the eyes. 

 

Dragonflies are very strong fliers, and to do this they need to have significantly more muscle mass stored within their rigid exoskeleton than damselflies. Compare the thorax (where the wings are attached) of these four local dragonflies—Blue Dasher, Ringed Emerald, Chalk-fronted Corporal, Hudsonian Whiteface—to the smaller thorax of three damselflies which appear following.

Northern Spreadwing, Swift Forktail and Tule Bluet. Damsels are much smaller overall.

Wing structural differences are the most important features to separate the “damsels” from the “dragons”. Dragonfly fore- and hindwings are different shapes, with the hindwings having much wider bases than the forewings. Damselfly wings are the same shape, all four wings with narrow bases. Also, damselflies have “hinges” that allow them to fold their wings over the abdomen, dragonflies do not.  “Spreadwing” damselflies are capable of folding their wings but prefer a partially open position at around 45 degrees under most circumstances.

Note how most dragonfly eyes touch in the midline (i.e. Variable Darner), whereas damselfly eyes are positioned more laterally on the head (i.e. Western Forktail).

The Pender Harbour area is renowned for some rarities on the Sunshine Coast, both butterflies and dragonflies. Pender Hill seems an unlikely place to find dragonflies, but this is not the case. It appears that some species practice “hill topping” like some butterfly species. Males of species like the Variegated Meadowhawk patrol the dry moss and lichen covered rocky outcrops of Pender Hill in search of a female.

The Spiny Baskettail is one of the rare local species known only from the Pender/Egmont area. This species lays gelatinous egg masses near lake margins. 

On May 21, 2021, Jenn Blancard reported an emergence of adults from Garden Bay Lake, and a week later I photographed a male atop Pender Hill. So please be vigilant this spring and if you see any egg masses or witness adults emerging around any of the lakes in your area, .....

 

please let me know at:

(randrudland@gmail.com)

 so it can be documented.

egg mass.jpg

In summary, dragonflies and damselflies are critically important apex predators in marsh, wetland, and lake ecosystems as both aquatic (larval stage) and aerial (adult stage) predators of diverse prey groups ranging from minnows to tadpoles and other insect larvae in the water, to mosquitoes, midges and even other Odonates out of the water.


They also are a significant food source for many of our nesting birds, like this Red-breasted Sapsucker returning to feed newly emerged damselflies to its nestlings,....

woodpecker.jpg

or this Cross Orbweaver spider with an Autumn Meadowhawk in its grasp. 

Rand Rudland

We are very grateful for this expert submission by our guest-writer, Rand Rudland.

Rand would like to alert you about a pamphlet, titled “Odonates of the Sunshine Coast” with information on forty of the most common local Odonates. To obtain your own copy they are available at the EarthFair Store in Madeira Park. 

 

We also point out that in 2019, our guest writer created a web initiative at naturalist.ca  called  “Dragonflies and Damselflies of the Sunshine Coast, BC”. This website investigates the dragonflies and damselflies of the wetlands and adjacent areas on the Sunshine Coast in order to expand the local knowledge of their distribution.

Associated with this work you will find, below, a clipping of a map accessible on the web and which documents the sightings in and around Hotel Lake.  You will also find a link to this site in our reference section below.

A Few more Things about Dragonflies and Damselflies

 

Thank you again, Rand, for covering the topics of identification and life-cycle. It is our mandate and practice to expand on a few other areas and so we have gathered a bit more information to conclude this page in our usual way.  We could not resist including this colourful life-cycle graphic. 

As you can see Odonta begin life as free-swimming, predatorial larval stage nymphs. They spend 1 - 6 years underwater, where they breath through gills. They hunt mosquito larvae, aquatic insects, tadpoles, tiny fish and even each other.  A primary threat to these nymphs are fish, many of which are stocked annually. Eventually these nymphs moult into the final phase of their lives as flying insects.

 

In this final brief period as aerial predators, these beautiful flying insects demonstrate spectacular aerobatic capabilities as they hunt for insect-prey. Many sources state that dragonflies are regarded as the fastest flying insect in the world. The Smithsonian Institute states:  “Dragonflies are known to travel at the speed of 35 miles an hour” or 56 kph. With their high speed, and exceptional maneuverability, they are both effective and ferocious at catching their insect prey. The following beautifully filmed video covers the entire life cycle in stunning close up cinematography.

Extraordinary Eyes

They have three small simple eyes called ocelli and two enormous compound eyes, which contain 30,000  hexagonal ommatidia or facets which are photoreceptors sensitive to a wide range of wavelengths of light. Thus, it is believed, they can visualize perspectives that are not available to humans. The combination of binocular vision and a high sensitivity to motion detection make them highly efficient airborne hunters.

Although they have a blind spot directly behind them, they otherwise enjoy nearly 360-degree vision. They see well in the daylight but not as well when night encroaches.  With the approach of twilight, dragonflies begin to loose their visual acuity and air superiority.  At the same time bats emerge from their daytime domiciles, and start hunting using echolocation (they emit voice calls and listen for echos). Bats, using low level sweeps over Hotel Lake, take over the hunt for insects which would include dragonflies if they were flying.  But dragonflies instinctively take refuge from the bats by perching unseen and  motionless on plants thus avoiding detection until dawn.

Prey

Touted as the fastest insect aloft over Hotel Lake, our dragonflies have unparalleled flight superiority during daylight and pursue all types of insects including bees,  mosquitoes, flies, moths and butterflies

Jaw & Mandible

They have a trap-like lower mandible, hence the “odon” in their name, referencing teeth.

They hunt using their feet to catch prey and then, while continuing to hunt, feed the prey into their mouth which features a highly dexterous trap-like lower jaw (mandible).  This hunting process is so efficient they can catch and eat half their weight in flying insects in an hour. 

Humans and Dragonflies - Brief Encouters

IIn July or August, take a break and find a spot to sit in your garden or on the shores of Hotel Lake. In just a few minutes a dragonfly, one of a species that pre-existed dinosaurs by 100 million years, will likely land on your knee or toe or perhaps the knuckle of your forefinger. Its large size, bright colours and energetic flying behaviour can make it seem threatening and the thrill of this magical encounter  can easily be eclipsed by modern phobias and nicknames such as “devil’s darning needle” and “horse-stinger”. But does it sting, does it bite, and does it transmit disease?  Unanswered, these questions may spawn fear or an instinctive impulse to swat the creature aside. What a shame that would be!  Let's not swat but; instead, let's seek answers, overcome fear with knowledge and find ways to understand and appreciate this wildlife neighbour.

First of all dragonflies don't have stingers, so they can't sting you!

 

If provoked, dragonflies will try to escape but might, if trapped and in self defence, be forced to bite and even then, only the largest of dragonflies are able to break human skin. Keep in mind that dragonflies have no interest in biting you for a blood-meal as mosquitos do. 

Unlike insects such as mosquitos and ticks, dragonflies are not known to transmit disease to humans.

Endangered or Invasive Species

Are these stunning creatures at risk here in BC?  We found a 2002 reference stating that some 23 species are considered rare or potentially at risk. The reasons include the loss of habitat, (wetlands, streams, lakes) and development projects that destroy such habitat.

Climate change also introduces stress on the dragonfly when natural wetlands and freshwater lakes and streams are diminished by prolonged periods of warmer and drier weather.

While in their underwater nymph/larvae stage, they are a food source for fish. Some estimates suggest that 99 percent of dragonfly nymphs do not survive to become adult flying dragonflies. If this is correct, the dragonflies and damselflies that we see represent just one percent of the total born into their aquatic environment. 

 

How can Humans Help and Respect

Dragonflies, should be viewed as highly beneficial.  They take flight in the spring and summer and immediately start hunting insects and in particular mosquitoes. They are not aggressive and represent no threat to humans and they are simply delightful to watch. They only live as aerial predators for a few weeks and months.  It will not be until the following spring and summer that we will we see the next generation.

 

We can all help by simply reading about and knowing more about these wildlife neighbours.  If we make the effort to observe these natural creatures and understand their life cycle we will all be better able to understand and make personal decisions that help to preserve their habitat and accommodate their needs. And when we see development plans materialize, we will be better able to speak for this species.  Who will do this if we don’t.

Photo taken by Brent Cooke, formerly Director of Exhibitions for the Royal British Columbia Museum in Victoria B.C. for 33 years and currently a museum consultant and bronze artist.

Enjoy this stunning video from National Geographic

References

 

2019, Naturalist.ca, Dragonflies and Damselflies of the Sunshine Coast, BC. This web initiative, was created by our guest writer, Rand Rudland, in 2019 to investigate the dragonflies and damselflies of the wetlands and adjacent areas on the Sunshine Coast in order to expand the local knowledge of their distribution within the footprint of the Sunshine Coast Regional District.

https://www.inaturalist.org/projects/dragonflies-and-damselflies-of-the-sunshine-coast-bc-canada

2002, Rare Dragonflies of British Columbia, Ministry of Sustainable Resource Management Ministry of Water, Land and Air Protection

https://www2.gov.bc.ca/assets/gov/environment/plants-animals-and-ecosystems/species-ecosystems-at-risk/brochures/rare_dragonflies_bc.pdf

Meet Casey Piercy at Medowia.com: Wonderful and informative narratives about every facet of dragonflies.

https://meadowia.com/category/dragonflies/

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