Chalk-fronted corporal dragonfly - how many instars do dragonfly larvae undergo?

Chalk-fronted corporal dragonflies.  Left: Male  Right: Female.  Dutch Lake, Clearwater, BC.

I have always loved dragonflies.  As a child, I used to throw small rocks near them and watch them chase the falling stones as if they were a potential meal.  I learned that they have a favoured perch and would approach it when they left; eventually I could place my finger there and get them to land on it.  I have photographed over a dozen species I have identified and many more I have not.  

While visiting Clearwater, BC, this summer, I managed to photograph a male and female chalk-fronted corporal dragonfly.  The term "corporal" comes from the pair of stripes found on the top of their thorax (just in front of the wings - you can see it in the above images.  The male I have is young and has not "earned" its stripes yet - click here to see a mature adult).  A corporal in the army has two stripes, as opposed to a private (one stripe) or a sergeant (three stripes).

They are a type of skimmer, a large group of dragonflies that have the habit of skimming close to the surface of the water.  The chalk-fronted variety has a habit of perching on the ground, often on rocks in sunny places, perhaps to extract whatever warmth they can find.  As I walked down the wooded path near the lake, there were hundreds of them that darted about.  They no doubt were benefiting from the people who disturbed settled insects or insects that were following in the hopes of getting a blood meal.

The aquatic nymphs (naiads) are ambush hunters, lying in wait for a meal to pass their place of hiding.  The tiny, freshly hatched young take only the smallest prey, such as water fleas (Daphnia), but their meals become progressively larger as they mature.  Dragonflies are unusual in that they have a larger number of instars than most other insects.  Certain fly species have 3, other fly species have 5, beetles may have up to 5, and those in the Hemiptera may have as many as 9.  Dragonflies have anywhere from 8 to 17 instars, depending on the species and environment.  Skimmers have between 9 and 13.

I would have liked to see them with their "corpral" badges fully developed, but that is for another time.

Thanks for reading.

Eric Svendsen     www.ericspix.com


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