By Dorothy Dobbie
The dragonfly is a wonderful creature, often credited with eating mosquitoes. While they do this, mosquitoes make up only a portion of their diet. That’s because dragonflies need the temperature to be about 25 degrees Celsius in order to fly so they are only active during the heat of the day when mosquitoes are hiding in the cool grasses and shadows. Females lay their eggs in water where emerging larvae can readily access mosquito and other larvae.
The rest of the dragonfly diet is quite varied, consisting of midges, butterflies, moths, flies, even smaller dragonflies. The larvae will eat anything that moves and that they can get their cup-like, extendible bottom lip around.
Dragonflies have incredible eyes that give them a 360 degree view of what’s going on in all directions. While they don’t see the detail we do, they can detect motion at 1/300th of a second and, with their ability to fly like a helicopter, they can quickly respond by moving upward, downward, forward or even backward. They can also hover. Their flight speed varies between 36 to 54 kmh with a cruising speed on 16 kmh.
Remember that I said that dragonflies are heat sensitive? They can also get too hot. As the temperatures soar, some will hide in the shade – where they no doubt encounter some tasty treats – but others will sort of perch in a handstand with their tails pointed towards the sky. This is to expose as little as possible of their bodies to direct sunlight, helping them regulate their temperature. Clever little creatures, aren’t they?
Even so, they have their challenges with birds, frogs, toads, newts and fish – even larger dragonflies – seeing them as edible.
If you want to attract dragonflies, give them a place to lay their eggs – namely, a pond with some plants in it. You need the plants because that’s where they deposit their eggs. But even without this, if you have a healthy ecosystem in your garden, you are bound to be hosting a healthy diet for them to eat.
Dragonflies and damsel flies often appear in the same vicinity. They are closely related, being in the order Odonata. While most of us would differentiate between the two by their size and delicacy, this isn’t as reliable as looking at their wings. Damselflies wings are all the same size and shape whereas the hind wing of dragonflies is bigger than their forewing. Dragonflies also perch with their wings spread, while damselflies fold their wings close to the body.
Dragonflies spend most of their lives underwater as nymphs or larvae, emerging to take wing, mate and lay eggs.
What colour is a dragonfly? As you have probably observed, they come in almost any colour of the rainbow: blue, yellow, orange, pink, red, purple, green, brown, black, gray . . . Many have clear wings, but some have coloured or iridescent wings of many colours. Some Japanese male dragonflies can shift colour from yellow to red, indicating their sexual maturity. We have 98 species of dragonfly and damsel flies in Manitoba, so chances are you will see a variety of colours.
And we are keeping an eye on these guys. The University of Manitoba has been tracking the migration patterns of the insect by gluing tiny tracing devices on their abdomens. They are particularly interested in green darners, which apparently migrate to Mexico and the Yucatan Peninsula at this time of year.
Dorothy Dobbie is the publisher of Manitoba Gardener magazine. She and her daughter also produce a weekly email called 10 Neat Things. If you would like to receive it, go to www.localgardener.ca and sign up.