Sat. Feb 24th, 2024
Green bug crawling up a rock on the edge of a lake

Today’s post comes from Evan McCaul, Northwest Parks Ecologist in Ontario.

While conducting an ecological inventory of Brightsand River Provincial Park, Ontario Parks staff witnessed and recorded a large-scale emergence of dragonflies, including a Dragonhunter, the largest clubtail dragonfly in North America!

Brightsand River Provincial Park is a 41,250 ha waterway park located 150 km (by air) northwest of Thunder Bay. The site was visited in June by Ontario Parks staff, who conducted an inventory of the natural scientific features of this protected area.

Fast-flowing river with conifers on the banks, under a blue skyBrightsand River Provincial Park

Natural science field studies are important to observe ecological conditions and increase understanding of natural resources within Ontario parks.

Map with a large lake in the upper right corner.Location map of Brightsand River Provincial Park

king of dragonflies

The dragon hunter usually hunts other dragonflies. When prey is caught, it is eaten head-on!

Large dragon fly held in a handThe dragon-hunting dragonfly

This dragonfly also consumes other large insects (moths and butterflies). The exuviae (empty larval shell) seen in the photo below are quite distinctive due to their large, fan-shaped abdomen.

Exuviae or empty larval shell

An ancient history on the planet.

It is known that dragonflies were one of the first winged insects that evolved about 300 million years ago. They belong to an order called Odonata or “the toothy ones.”

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Like most other insects, they have a head with two antennae, a thorax with six legs and four wings, and an abdomen. Its life begins as an egg, laid in or near water. These eggs develop into aquatic larvae and it is in this stage where dragonflies spend most of their lives.

From larvae to dragonfly: the emergence

Depending on the species, the aquatic stage can range from a few months to four years or more. When the larvae mature, they head to the water’s edge and crawl toward rocks, logs, emerging structures (e.g., docks), or the shoreline itself.

Green dragonfly without outstretched wings, on the shoreDragonfly larvae, before emerging.

Once anchored to the shore, the larvae “burst” and the adult dragonfly emerges from within the larvae. When they first emerge, they will have a mass of wrinkled wings and a short body. From here, the transformation occurs quite quickly and, within about 30 minutes, the wings are “pumped” with hemolymph (insect blood) and their body grows to full size.

Green insect crawling on a rock at the edge of a lakeDragon Slayer Appearance

They may then fly to a shelter to dry and harden over the next few hours or days. An emerging dragonfly is very vulnerable during this time, as it cannot escape predation from frogs or birds.

dragonflies in the sky

There are more than 5,000 species of dragonflies in the world, and of those, about 130 species have been recorded in Ontario. Adult dragonflies have a relatively short lifespan relative to larvae.

While larvae can live more than four years, adult dragonflies have, on average, four to six weeks to mature, feed, find a mate, reproduce, and lay eggs for the next generation.

Fearsome and skilled predator

Dragonflies have two pairs of wings so they can fly up or down, back, fly upside down, and hover to chase and capture prey. In addition, they have almost 360-degree vision that allows them to quickly detect and hunt for their food.

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Colorful dragonfly eating another dragonflyA dragonfly devouring a smaller one.

Dragonflies are great hunters both in their larval and adult lives. In their larval stage, they live in water and eat anything that comes close to them, including aquatic insects, tadpoles, and small fish. In fact, dragonfly larvae are often the main carnivores in freshwater habitats without fish.

As adults they eat flies, mosquitoes, grasshoppers, butterflies, flying ants and even other dragonflies, which they catch while flying.

Formidable adversaries

Ontario parks staff wear wellies with a net in the lake, searching for dragonflieshunting dragonflies

Dragonfly larvae and adults are themselves a food source for other animals. The nymphs are prey for fish and amphibians, while the adults are prey for a variety of birds, including rusty blackbirds, which were observed in the Brightsand River flying back and forth along the coast, hunting dragonflies to feed. to their offspring.

Odonates are threatened not only in Ontario, but elsewhere as well. Climate change may be one of the most important factors in the reduction of odonate populations. Drought causes shallow ponds to dry out and when these sites are dry for several years, their odonate fauna will disappear.

Not only have droughts become more frequent, but also heavy rains, and streams are always at risk of being affected by flooding. Fast-moving water can wash away a river bed, removing silt and sand essential for larval habitat. Rising water can kill emerging individuals.

Science to the rescue!

That’s where surveys, like those conducted by Ontario Parks, are vital to understanding the distribution and habitat preference of our dragonfly and damselfly populations.

Canoe full of equipment, on the shore of a beachExploring the Brightsand River Coast

Studying odonates not only provides important scientific data, but is also a fascinating hobby!

If you would like to learn more and/or contribute your observations to expand the knowledge base on this species, check out iNaturalist, an online database of species observed in Ontario and around the world.