Daily Archives: July 16, 2008

Daylilies and dragonflies

Meadowhawk sp.

This is the time of year when my mom’s garden really reaches its peak. It’s a perennial garden, with many different types of flowers, shrubs and plants, but with a focus on daylilies. There are hundreds of cultivars of daylilies, you could fill up acres collecting every one. Mom doesn’t have that many; her collection is somewhere around a hundred cultivars, and was mostly limited by the space in the garden. Most daylilies flower from mid-July through August, and during this time the garden is a riot of colour. The only natural flower colour that seems to be missing is blue, which they haven’t managed to create in the species, perhaps because blue is a structural pigment and isn’t formed through the same processes that produce reds, oranges and yellows. Each bloom on a daylily only lasts one day (hence the name), and a walk around the garden each morning will be just a little different from the previous day, with some cultivars blooming, others not, multiple flowers on some, and first blooms of the summer.

Meadowhawk sp.

For the last couple weeks, we’ve noticed that the garden is full of these guys, little dragonflies, short and small by dragonfly standards, in red and orange. Dozens of them, all hanging around the garden. They’re meadowhawks, a type of skimmer. About the same length as the damselflies, they can be easily distinguished by their chunky bodies and wings, and oversized eyes. They’re fairly common dragonflies, but there are several species and telling some of them apart can be tricky. A number of species have orangey wing markings, but for those that don’t (and this includes the ones that occur here), the best characteristic is the face. Around here we’re likely to get White-faced, Cherry-faced and Ruby Meadowhawks. There is some overlap in face colour, just to make things confusing, but generally the White-faced have a pure white face, the Ruby has a straw-coloured face, and the Cherry a reddish face (although eastern individuals can be olive-yellow). The book Dragonflies Through Binoculars states that Ruby and Cherry-faced cannot be separated by face colour in the east. The Stokes Beginners Guide to Dragonflies also warns, “A meadowhawk with a dull yellowish or ivory face cannot be identified with certainty in the field.” Rather, definitive identification requires examination of the genitalia under a microscope. And, to throw a wrench in the works, Through Binoculars indicates that all three species hybridize in the northeast, such that intermediate individuals may not belong to one species or another but are instead hybrids.

Meadowhawk sp.

The brown individuals are all females, or possibly immature males. Male meadowhawks remain this brownish colour for about two weeks before obtaining the bright red of maturity. During this time they’re separable from the females by examining their genital structures, but I didn’t look that closely. It’s interesting how much of dragonfly and damselfly identification comes down to the genitalia. How do the insects know which species another individual is when courting? Are there little visual clues that we haven’t seen, or are too small for our naked eyes? Or do they use behavioural cues? It would be embarrassing to try to hook up with a female just to find your lock and key don’t fit; good thing dragonflies don’t get embarrassed.

Meadowhawk sp.

More than most other dragonflies I observe, meadowhawks like to perch at the tips of tall pointy things that stick out from the surrounding foliage. It was tough to get a photo of one actually on a daylily bloom because they would favour the long grasses, tall thistle stalks, and even the unopened daylily buds over the flowers themselves. Like all dragonflies, meadowhawks are predaceous, feeding on other insects, using their speed and agility to catch them. I imagine that perching in an exposed location like that offers them the best view of their surroundings, and potential prey, and also allows them to dart out after something without having to navigate around plants. If you watch a meadowhawk closely you can see it turning its head to focus on different things.

Meadowhawk sp.

I’ve noticed the occasional individual will adopt this pose while resting. It’s called the “obelisk position”, and its purpose is to minimize the surface area of the dragonfly’s body that is exposed to the sun. Since insects have no physiological ability to thermoregulate, they must change their behaviour to prevent overheating. Whereas we would simply sweat and cool down through evaporation, a dragonfly must either seek shade or, where shade isn’t available, or is impractical (such as in hunting in open areas), minimize their exposure to the sun. While most dragonflies are associated with water edges, meadowhawks, as their name implies, are often found in meadows or other open areas that may have minimal shade. Notice how small the dragonfly’s shadow is on the fern frond.

Also interesting to note, the above individual appears to be a male changing from its immature brown into its mature red colouration. You can see the red starting on the top of the abdomen in a couple spots.

Meadowhawk sp.

In taking close-up photos of a few individuals, I noticed that the pattern of colours and spots on their large compound eyes varied from one individual to the next. For instance, the above individual looks like it has pupils and is smiling at the camera, while the one below has more diffuse spots on its eyes. I wonder if this is a difference in species, in sex (since immature males are the same colour as females), or simply individual variation?

Meadowhawk sp.

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