by Jessica Johnsrud, education coordinator

A couple of weeks ago, I was walking along a Lake Michigan beach when I stopped in my tracks. There were hundreds, maybe thousands, of large dragonflies flitting about. I watched as tiny helicopters darted quickly from side to side. Some hovered, suspended in air, many at eye level. It was quite a spectacle!

The majority of the dragonflies I saw at the beach were Common Green Darners. They are large, about three inches in length and have a green thorax (the part of the body where the legs and wings attach). The males have a blue abdomen and the females have a reddish-brown abdomen. As the name suggests, this is a common dragonfly species found throughout North America. As they fly, they eat a large variety of soft-bodied insects such as mosquitoes, gnats and flies.

Scattered in the group was another dragonfly species called the Black Saddlebags. This dragonfly is 2-2.25 inches long and has a dark body. Its wings are clear except for a dark spot near the base of the hindwings where they attach to the body. This identifying feature gives the illusion that it’s carrying saddlebags. Like the green darners, they also eat soft-bodied insects, but are especially good at eating mosquitos.

Both of these dragonfly species start their lives as an aquatic nymph called a naiad. As they grow, they shed their exoskeleton, each time looking more like an adult dragonfly. For the final molt, the naiad will crawl out of the water and the adult dragonfly bursts through the exoskeleton, with the head emerging first. The fresh dragonfly, known as a teneral, needs a little time for its wings and body to fully extend and dry before it can fly off to forage.

Like many songbirds, black saddlebags and green darners migrate south in the late summer and early fall. The difference is that it’s a one-way trip and upon arrival, the dragonflies lay eggs and die. The new generation will make the journey back north in the spring. There is also a resident population of green darners that over-winter as naiads in the water and emerge as adults in the spring.

I’ve always had a love for dragonflies and enjoy watching them zoom around in the sky. As fall approaches, I like to take a few extra walks along the lake, hoping to observe these dragonflies taking off for the season.

Photo from wikipedia