Dragonflies and Damselflies
by Michael Holmes
Insects have a very ancient lineage in the history of life on Earth, extending back at least 400 million years. In comparison, the very earliest mammals formed about 120 million years ago. Needless to say, insects have been successful survivors far longer than Homo sapiens. Insects are thought to be among the first land animals, likely evolving from aquatic crustaceans. And some insects have not changed much from their early ancestors.
Meganeura monyi was a prehistoric insect that closely resembled modern dragonflies. It had a wingspan of more than 75 cm (2.5 feet), making it the largest known flying insect ever to appear on Earth.
Today's dragonflies are much smaller than Meganeura, but are relatively large among other insects in our area. Their often colourful bodies and iridescent wings are a pleasing sight on summer days.
There are a variety of dragonflies around our co-op including the Common Whitetail (Libellua lydia), named for the male's bright white abdomen. There are also red dragonflies and gold ones, ones with spotted wings and ones with stripes. There are also darners, large dragonflies with black bodies decorated with vibrant blue and green markings. The diversity of dragonflies is quite exquisite.
You can often find dragonflies perched on flat, open surfaces like sidewalks or patio stones. This is because the concrete absorbs and retains heat. Dragonflies, like all insects, are "cold-blooded", thus rely on exterior conditions to control their body temperature.
Dragonflies are predators, preying on smaller insects such as mosquitoes. Many years ago I attended a summer camp where I was surprised by the lack of mosquitoes, despite being in a heavily forested area by water. One sunny evening I discovered why the camp wasn't plagued by mosquitoes. The entire shoreline of the nearby lake sparkled with the wings of hundreds of dragonflies as they feasted upon mosquitoes and their larvae. Ever since, I have welcomed the sight of dragonflies, both for their beauty and their convenient appetite.
Damselflies are similar to dragonflies in many ways, but can be differentiated by how they hold their wings while at rest. A damselfly closes its wings along its back, while a dragonfly keeps its wings outstretched when it lands. Also, usually dragonflies are larger and more robust than the relatively small and delicate damselflies.
There are many damselflies in the area. Bluets are quite common in the co-op and can be identified by their slender, blue bodies.
One of the most beautiful damselflies is the Ebony Jewelwing (Calopteryx maculate), possessing bold black wings and a shimmering emerald body. Mating pairs of Jewelwings could be observed along the banks of Laurel Creek earlier in the season.
More recently the creek displayed a dazzling show of American Rubyspots (Hetarina americana). Males of this species have red or bronze bodies with brilliant red spots at the base of their wings. The females have green bodies with slightly duller red spots (photographed). Streaks of fiery red and sparkling gold could be seen dancing above the surface of Laurel Creek, as the pairs courted in the sunlight. Adult Rubyspots do not stray far from the streams where they are born and an adult female will dive completely underwater to lay her eggs.
Both damselflies and dragonflies are born in water, beginning life as aquatic predators. Only later does the nymph crawl onto dry land, echoing its distant evolutionary past, where it will molt its casing to emerge as a flying adult.