Noticing Nature #6 : Dragonflies and Mayflies

Wednesday 15 October

Odonata (Dragonflies) and Ephemeroptera (Mayflies/Damselflies)

There are so many reasons to fall in love with dragonflies. They have intriguing stories to tell us. They make our world a more beautiful place. And they are scrappy survivors.”

― Cindy Crosby, Chasing Dragonflies: A Natural, Cultural, and Personal History

If you see an insect with a long thin body at rest and its wings are laid out at right angles to its body on either side like aeroplane wings then you are looking at one of the species of Odonata. Looking for insects of this group in the summer months is becoming a popular diversion for birders in the period when the birds are harder to find after nesting and no longer needing to sing a lot. I have heard a couple of them refer to themselves as “Odious Oders”.

“Odes” are a group of species with aquatic larvae. Both larvae and adult forms feed on live prey. Consequently, search for them in mid-summer around streams, ponds, boggy areas and the banks of rivers. They occasionally turn up in gardens, especially if there is a garden pond nearby that may have held nymphs. There are wetland locations away form rivers too that you should check out.

Dragonflies

There are between 30 and 40 species reported in my study area, from a half dozen subgroups. Of these the Hawkers or Darners (Aeshnidae) include some of the largest of the dragonfly species. One common species, where I am anyway, to look out for is the Canada Darner (Aeshna canadensis) which can be seen feeding within forest or swamp boundaries throughout the daylight hours. Then we have other dragonfly groups such as the Clubtails which have a widened area at the end of the body from which the name is derived. Also to be found are the Baskettails, Meadowhawks, Skimmers and Spreadwings.

Dragonflies are characterized by having a thick thorax and the “waist” is barely noticeable. Wings are broad and sturdy and at rest are held outstretched horizontally, perpendicular to the body. They have large compound eyes that meet or nearly meet at the top of the head. They are powerful, fast fliers which often patrol open water or sunny perches. They may hover briefly before darting away.

Twelve-spotted Skimmer

Autumn Meadowhawk

Prince Basketail

Damselflies

There are fewer species of Damselflies. One that I see most years is the Tule Bluet (Enallagma carunculatum). A smaller species with bright blue segments on its abdomen. Compared to the big dragonflies these species are quite dainty for the most part. If there are rushes about, along the water courses and open drains for example, then almost certainly there is a chance of seeing Tule Bluets and relatives flying. Their aquatic nymphs help to control mosquito larvae while the adults feed on small flying insects, flies, small moths, aphids and mosquitoes too.

Damselflies have a slender, delicate thorax; with a pronounced waist between the thorax and abdomen. Wings are held, at rest, folded together over the back, like a “closed book” and are narrow, delicate, with the front and hind wings being roughly equal length. Eyes are separated, sitting distinctly on either side of the head. They are weaker fliers than dragonflies, and often seen fluttering close to vegetation and water edges.

Tule Bluet

Mayflies

There are a small number of Ephemeroptera, true Mayflies, each summer. Unlike the Dragonflies, the Mayfly larvae feed on detritus and other plant materials, and a small number of species may feed on insects. The adult Mayflies do not feed at all, simply busying themselves briefly with reproduction. The larvae live in water for around a year while the adults die after a couple of days, hopefully having mated and laid eggs in the interim. North Americans will certainly recognize Mayflies, commonly known as “Shad Flies” - these are the pale insects that cover our windows and doors and cars when there is a mass emergence in the height of summer. These mass emergences of Mayflies make an irresistible feast for birds. Two Mayfly/Shad Fly species in this area are the Emergent Mayfly and the Giant Mayfly (Hexagenia limbata).

The bodies of mayflies are thin, almost thread‑like, with long, hair‑like tails (cerci) at the end of the abdomen. Wings are usually held flat or slightly angled over the back. Mayflies are short‑lived as adults, often just a day. There may be swarms of them near streams or lakes, especially at dusk.

The Giant Mayfly.

---

• Next week we will wrap up the main insect groups by looking at Grasshoppers, Crickets and a couple of little groups you may never have heard of.