A photo essay by Peter Taylor
The clubtails (Gomphidae) are a diverse family of medium-sized to large dragonflies, with almost a thousand species known worldwide, a dozen of which occur in Manitoba. They are so called because most species have a clublike swelling towards the tip of the abdomen (primarily segments 7 to 9). The Midland Clubtail (Gomphurus fraternus) is a common eastern North American species that breeds in lakes and rivers in a broad band across southern Manitoba. A distinct subspecies (G. f. manitobanus) occurs in the Red and Assiniboine rivers, while the nominate race (G. f. fraternus) occurs in the Winnipeg River system and elsewhere in southeastern Manitoba. This photo essay is a spin-off from an interpretive signage assignment on this dragonfly for Pinawa’s Ironwood Trail alongside the Winnipeg River.
PHOTO: EMERGING NYMPH
After probably two years living as ambush predators in the river bed, larval Midland Clubtails (called nymphs or naiads) start to emerge around the end of May, reaching a peak in late June. One can watch their transformation to adult dragonflies on docks, boat covers, and other waterside objects. After cracking open the nymphal case and moving a little distance away (leaving the empty case or exuvia), the squat and rather ugly insect gradually unfolds its wings and expands its abdomen until it attains the elegant, aerodynamic adult form.
During this transformation, it turns 180 degrees at intervals, apparently to assure uniform drying and an accurately symmetric final shape. The transformation is a delicate process, and minor deformities are not uncommon.
PHOTO: IMMATURE DRAGONFLY
When the dragonfly is newly transformed and capable of only limited flight, the body has a drab olive colour with little contrast in its markings and a “wax-coated” look, while the wings have a delicate appearance like plastic wrap.
PHOTO: LATER IMMATURE STAGE
Over a day or two, the fully hardened, robust young dragonfly develops a striking black-and-yellow pattern.
Details of the pattern of stripes on the thorax and spearhead-like markings on the upper side of the abdomen help us to distinguish between different clubtail species. Male dragonflies, like this one, are usually slenderer than females, and there are subtle differences in their markings.
PHOTO: MALE CERCI
The precise shape of the male’s cerci (reproductive appendages at the tip of the abdomen) also provide important identification clues – for some dragonfly species, they may be the only reliable identification feature.
PHOTO: FISHFLY MEAL
On the Winnipeg River, peak emergence of Midland Clubtails coincides with the peak season for mayflies (fishflies), providing the young dragonflies with many an easy meal.
PHOTO: MATURE COLOURS
Within a few more days, much of the yellow coloration changes to a dull grey-green, providing camouflage on gravel surfaces or lichen-covered rocks; the yellow colour persists longest in the markings towards the abdomen tip.
PHOTO: MALE WITH HORSEFLY
Hiding in plain sight on rocks, trails, and low vegetation, both males and females dash out in a quick burst of flight to capture a wide variety of insect prey; the tactics are much like those of a goshawk or other woodland raptor. While some dragonflies have earned a reputation as “mosquito hawks”, Midland Clubtails generally take larger insects, ranging in size from horse flies (above) and small butterflies up to other dragonfly species almost as large as themselves.
PHOTO: FEMALE WITH BRUSH-TIPPED EMERALD
This female Midland Clubtail has captured a Brush-tipped Emerald dragonfly (Somatochlora walshii). Biting first at the head and neck, a Midland Clubtail taking another dragonfly suggests a lion with a wildebeest – Serengeti action in miniature. The prey is then quickly dismembered, wings and legs falling aside as the body is devoured.
An interesting dragonfly behaviour on hot, sunny days is “obelisking” – perching with the abdomen raised to point at the sun, apparently to reduce sun exposure and help maintain suitable body temperature. Note how small a shadow this female casts.
PHOTO: FEMALE WITH CLEARWING MOTH
A week or so after emergence, Midland Clubtails start to range more widely, following roads, trails, and clearings up to several kilometres from their natal waters. This female captured a clearwing “hummingbird” moth (Hemaris sp.) at Milner Ridge, well west of the Winnipeg River where she likely emerged.
PHOTO: MATING PAIR
This mating pair was also photographed near Milner Ridge. The male’s head is at the top. The female will have a long flight to find suitable water to lay her eggs.
PHOTO: SPIDER WEB
Fierce predators though they are, Midland Clubtails face a variety of hazards. This ill-fated individual blundered into a robust spider web not far from the Winnipeg River.
PHOTO: AGING INDIVIDUAL
If they survive such hazards, adult Midland Clubtails are quite long-lived, and the last individuals can be seen well into August. Its markings dulled over time, with battered wings, this male is a mere shadow of his former self.