A Nicely Frosted Competitor

Saturday-Sunday, May 10-11, 2025

A Nicely Frosted Competitor

Today’s special animal friend is the Common Whitetail dragonfly, Plathemis lydia. This insect, found throughout North America, belongs to the family Libellulidae, “skimmers and perchers,” which is the largest family in the order Odonata, “toothed ones,” which includes all the dragonflies and damselflies.

Common whitetails live near ponds, marshes, or slowly flowing streams, where they eat mosquitoes or other small flying insects. They feed by “hawking,” catching the prey out of the air during flight. Males are about 2” long with a stocky thick body. In immature males, such as the one hanging around the archery range on Saturday, the abdomen is dark. Mature males have a frosted white coating on the abdomen, a feature called “pruinescence.” It is highly visible to other male dragonflies, who think, “Oh, he's big and bad!” and avoid the territory of a nicely-frosted competitor.

Males compete for territories near the bank of a body of water. A territory may include nearly 100 feet of shoreline. To police their territories, male dragonflies have highly developed wing muscles, comprising most of their body mass. They have one of the highest “Flight Muscle Ratios” of any animal; this is calculated by dividing the flight-muscle mass by the body mass. Males with a lower FMR have smaller territories and less breeding success, but they live longer than males with higher FMRs, who literally live fast, love hard, die young.

The wings have a translucent, mesh-like appearance and are composed of veins and membranes. The common whitetail’s wings have irregular, dark patches over the mesh. It looked like shiny copper on the young guy at the range, but that must have been an effect of the morning sunlight. Their ability to fly requires extraordinary oxygen uptake. The explanation is full of long words I have never seen.

Females are slightly smaller and have a brown body. They lay eggs, “oviposit,” every few days. Flying around the body of water, they look for a territory where the eggs maybe won’t be eaten. The female will mate with the male who is guarding that territory. Because of the positioning required, the mating requires the female’s cooperation. The male removes sperm from other males from the female’s abdomen and deposits his own. That done, the female goes to lay the eggs in the water, and the male guards her until she has done so. After that, off she goes, and he waits for another female to come by.

The eggs are vulnerable to predation from fish and tadpoles. They hatch into “nymphs,” aquatic macroinvertebrates a few millimeters in size, and they spend most of their lives in this form. Two years or more is common. Nymphs have large eyes, six small legs, and gills in their rectum. They breathe by using muscles to draw water in and out of their rear.

They are voracious predators of other insects’ eggs and larvae, infant crayfish, small fish, and tadpoles. They are eaten by other insects’ nymphs, adult insects, fish, frogs, and birds. Around 99.9% are eaten or dry out before they reach adulthood. When the environmental conditions are right, usually spring, mature nymphs climb up a blade of grass or a reed. Their bodies split open, and an adult dragonfly emerges. The common whitetail lives only a few weeks, eating and mating and laying eggs.

This species is numerous and widespread. The nymphs are somewhat resistant to water pollution, but try not to pollute bodies of water, just on general principle!