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Dog-day Cicadas mating in the heat of summer
Dog-day Cicadas Mating in the heat of summer
On a recent sultry summer day here in Toronto, Ontario, I went out to the garden to tend to some chores. Imagine my surprise, as I bent to the task of deadheading my Gaillardia, when something clipped the side of my head. Seconds later, I noticed a pair of Dog-Day Cicadas mating where they lay on the pavement of the street.
A couple of weeks earlier, this newly-emerged Dog-Day Cicada clung to a concrete sculpture in our backyard. This adult Cicada would have recently surfaced from the ground where it spent the past 2-3 years as a nymph. Once their transformation is complete, those nymphs that are fully developed emerge from the soil, but their emergence is not synchronized. Because every July and August there is a percentage of Dog-Day Cicadas that show up, they are called annuals. The nymphal stage of some species of cicadas can be as long as 17 years, and they are referred to as periodic cicadas.
Beside the newly-hatched adult Cicada and affixed also to the sculpture was the exoskeleton inside of which the nymph spent the previous stage of its life. Shortly after they hatch from eggs, nymphs tunnel into the earth where years pass as they grow through several stages of development or instars.
A female Dog-day Cicada lays her eggs on a tree limb in a slit that she fashions with her ovipositor. The puncture in the bark allows tree sap to seep out so the nymphs have ready access to sustenance when they first hatch. Once they relocate to their subterranean habitat, nymphs locate plant roots from which to acquire liquid, and they burrow from one location to another during their lengthy stay underground.
By the time a nymph has grown into an adult, it is ready to return to daylight, climb up a tree trunk and shed its exoskeleton. A cicada does not always choose a tree as a spot to await this transformation because we have found exoskeletons clinging to raspberry canes, the garage wall, our garden arbour as well as this concrete rabbit. After shedding its exoskeleton, the new adult Dog-day Cicada remains stationary until the wings inflate with liquid and its skin hardens, then it begins to seek a mate since its adult life is short.
Getting back to the two Dog-Day Cicadas copulating at the edge of our suburban street, they provided me with unparalleled closeup views of their bodies. Two bulbous eyes set far apart on either side of a broad head, and short antennae between the compound eyes are the first characteristics I noted.
The pair of Dog-Day Cicadas were not content to remain in one spot, at least the one on the left was determined to crawl a distance toward the curb and onto some weeds that had eked out an existence in the cracked asphalt. The other cicada had no choice but to go along for the ride locked as they were together. The front wings are delightfully transparent with predominant green veins that are really noticeable near the base.
I was fascinated by the intricate colour pattern that resembled military camouflage wear. In fact, there are 3 different colour morphs of the Dog-Day Cicada, Green, Brown and Dark (almost Black). The two individuals that I was observing are Green morphs identifiable by the green with black markings on the dorsal surface behind the head and considering the green wing veins noted above.
When first I took note of the Dog-Day Cicadas on the street, of course I didn’t have a camera in my garden bucket so had to dash into the house all the while hoping they would still be where I last saw them when I returned to the end of the driveway. The process of copulating took at least 10 minutes, so after a few quick snapshots, I returned to my own work.
As a pair of adult Dog-Day Cicadas, their adult lives span a mere 4-6 weeks during which time all energy is put into finding a mate, breeding and laying eggs. When you hear the shrill, loud calls of what we used to call “hot weather bugs”, that is the adult male Dog-day Cicadas advertising for females or warning of danger. They have to be wary of predators like birds, bats, squirrels and a few species of insects.
Dog-Day Cicadas are so named because they are typically heard singing their loud buzzing and clicking noises during the hot dog days of late summer. An alternate moniker, Harvestfly, is also appropriate because their appearance coincides with the summer harvest. Because adult Cicadas spend most of their adult life in trees, they are sometimes referred to as tree crickets, but no matter what you call them, their noisy musical chorus of mating calls is a signature sound of summer.