Common green darner
As we transition from winter to spring, nature lovers should take a chance to stroll along North Idaho’s many streams, rivers and other bodies of water. If they are fortunate enough, they might catch a glimpse at one of the most relentless aerial predators of the insect world: the dragonfly.
As their name may suggest, they are terrifying to other insects, though completely harmless to humans. One species common in our neck of the woods (and in fact the most numerous species in North America) is the common green darner (Anax junius). Like other species of dragonflies, it isn’t born at the top of the food chain; it must first undergo one of the most incredible transformations in the animal kingdom.
Green darners are quite big as insects go, measuring between 2.7 inches and 3.3 inches long and possessing a wingspan anywhere from 3.5 inches to 4.5 in width. As their name might indicate, these insects are indeed bright green on their thoraxes (that’s the middle segment of an insect’s body).
However, full-grown male specimens have a dark purple stripe bordered by lateral stripes of bright blue across their abdomen, while full-grown females have rusty brown or purple abdomens.
Younger individuals of both sexes have red-colored abdomens.
A surefire way to tell a green darner apart from similar-looking dragonflies that share the same home range is to look for a so-called “bull’s eye” mark on its face. This characteristic mark is a black or brown dot encircled by a yellow and blue ring. The third part of their name comes from their resemblance to a darning needle used in sewing.
Like miniature hawks (or dragons?), green darners patrol their wetland habitats in search of suitable prey. This usually includes butterflies, as well as pesky insects like flies and mosquitoes. They also sometimes snatch up beetles from ground level or atop plants. This may come as a surprise, but unfortunately, dragonflies are incapable of breathing fire.
Do you remember when I said that dragonflies went through an amazing transformation before becoming apex aerial predators? Well, these flying insects actually begin their life hatching from eggs in late July or early August underwater!
Before becoming airborne predators, they stalk the shallow pools in which they were born. Baby dragonflies are called nymphs, and they have large eyes, a long, oval-shaped abdomen. Once they’ve crept close enough to a tadpole, frog, mosquito larvae, a small fish, or even a smaller nymph (sometimes of the same species!), their extendable lower jaw (called a labium) shoots out, snags the prey and reels it in for consumption.
Dragonflies remain nymphs for some 11 or 12 months, which is a long time by insect standards, before crawling out of the water and moulting. They emerge from their “nymph” exoskeleton as fully-formed adults ready to take to the wing.
Common green darners are absolutely fascinating insects that everyone should get the chance to see in their natural habitat. If you are able to get up close and personal, think about what the world must look like through the big compound eyes of this tiny aerial predator.
•••
Email Christian: animaladventures1314@gmail.com
