This week’s crawly has a perfect common name. Meet the river jeweling (Calopteryx aequabilis).
Their scientific name is spot on too: Calopteryx is from the Greek “kalos” (beautiful) + “pteron” (wing or feather).
There are only five species of jewelwings in North America, and only the river jewelwing can be found in Oregon.
Jewelwings are in the Family Calopterygidae – broad-winged damselflies. There are three non-jewelwing species of broad-wings, bringing the total number of species to eight. One other species, the American rubyspot, can be found in our area.
With so few species, seeing a broad-winged damselfly is a treat for sure. Luckily with the river jewelwing’s bright coloration and large size (1 3/4 to 2 1/4 inches) they are relatively easy to spot.
Pictured is a male river jewelwing. His rust-colored eyes tell us he’s recently hatched into adult form; they will darken to nearly black as he ages.
Females are paler with orange highlights on their bodies and have gray-green eyes.
They come by the “broad-winged” common name honestly. Compared to other types of damselflies, they do have very broad wings.
Like all damselflies, broad-winged naiads are aquatic. Adults are generally found on vegetation near water, especially in wooded areas near slow-moving rivers or streams.
River jewelwings can be found in the northernmost states and the southernmost provinces of Canada. They are widespread, but rare due to their specific habitat needs.
River Jewelwings need streams that are large enough to support underwater plants but small enough to have slow currents. All damselflies need vegetation surrounding the river to support the insects that they feed on. Most importantly, damselflies are sensitive to pollutants released into rivers.
Like all other damselflies, broad-winged are predators as naiads and adults. The naiads eat various types of soft-bodied insects including mosquito larvae, mayfly larvae, and other aquatic fly larva. They’ll even eat small fish. They’ll take up to three years to mature enough to emerge as adults.
Adults catch their prey on the wing; their excellent eyesight allows them to see small flying insects such as mosquitoes, mayflies and small moths. Their hairy legs help them catch their prey on the wing. Their favored mode of hunting is the “perch and swoop”. They’ll perch on stream or pondside vegetation then swoop out to catch a meal and return to their perch to dine.
Adults will emerge from June through September and will live for a few weeks. They’ll split that time between acting as pest controllers and looking for mates.
Males woo the females by finding a good body of water for egg laying. They’ll then perform a mating dance over the water source to show any nearby females what an awesome aquatic nursery they’ve found.
Females will submerge themselves underwater for up to thirty minutes at a time to lay their eggs on submerged plants. The eggs take between eight and 10 days to hatch and the naiads immediately start looking for tasty insects to eat.
River jewelwings have been found at Table Rock, along Bear Creek, by the Illinois River and in several areas of the Umpqua National Forest, so look for these sparkling beauties as you enjoy our natural areas over the summer months.
