A dog-day cicada. Photo: Bruce Marlin/Wikipedia Commons

A few days ago, I opened the front door to pick up the newspaper and was greeted by a large, bulky insect, a cicada, perched on the threshold and facing the door as if it were waiting for someone to let it in.  I gave it a nudge, and it skittered and tumbled away, half flying, half bumping, rattling loudly.  When I went back outside about an hour later, the cicada was still there, on its back, lifeless.

Such misunderstood creatures, these cicadas.  They appear during the warmest time of the year – in fact, the bug that showed up at my door was from the genus Tibicen, or dog-day cicada.  These insects molt shortly after they appear, leaving eerie-looking empty bug-shaped shells stuck to a tree trunk, a fencepost, or the side of your house.  After they molt, they congregate in trees and rattle away in search of a mate.  And within a week or so, you start seeing their bulky bodies littering the ground.

And then there are the 13-year and the 17-year cicadas, or “periodical” cicadas, so-named for their peculiar life cycle where they emerge en masse every 13th or 17th spring (depending on the species) to the horror of many squeamish humans.  I was living in Nashville, TN, during one such outbreak in 1998.  A lot of native Tennesseans prepared themselves for it (and by “prepared themselves” I mean “left the state”), and others sold T-shirts boasting that they survived the great cicada invasion of 1998.  The “invasion” did not disappoint.  Thousands of periodical cicadas – red-trimmed and smaller than the black dog-day cicadas – were absolutely everywhere for about three weeks.  And then they were on the ground, dead, crunching under your tires and feet.  So I ask you, should we pity the lowly, short-lived cicada, which shows up for a couple of weeks every year, just to mate and die?

Consider an even more extreme example of a creature that has an apparently short lifespan: the mayfly.  Mayflies are notorious for their truncated lives, some apparently living for no more than 30 minutes.  In Germany, the mayfly is known as Eintagsfliege, or one-day fly.  In France, it is called the “ephemere”: the ephemeral, the transient, the fleeting.

I’ve had plenty of first-hand experience with mayflies.  For the past six years I’ve been a member of StreamWatch, a volunteer organization that monitors the health of nearby streams.  We do this by taking samples from underneath the rocks in the stream bed and identifying the invertebrates (insects, snails, crustaceans, etc.) that call the river bottom their home.  The classes of invertebrates we find tell us what kind of state the stream is in.  Mayflies do not tolerate pollution too well, and so they are rare in impaired waters but one of the most common invertebrates we find in healthy streams.  But it’s not the adult form that we see – it’s always the immature or nymph stage that lives under water:

Left: A mayfly naiad, about 3/4" long, resting in a shallow stream (Photo: Rob Tilghman). Right: An adult mayfly (Photo: Richard Bartz/Wikipedia Commons)

Mayfly nymphs, or naiads (named after the beautiful young women of the water in Greek mythology) are autonomous, aquatic creatures, complete with six legs and a full set of gills.  They feed on algae and other plant material, and they can move quickly to escape a predator by swimming in an up-and-down motion like a miniature dolphin.  Mayflies will stay in this naiad state - fully functional except for the ability to mate - for a year or more before they pupate and transform into the adult mayfly that we typically see swarming and then dying within a day.  A year is not a bad life span for an insect - at the very least, it’s a lot better than the single day we usually attribute to mayflies.  What’s more, the adult mayfly is not much more than a flying set of reproductive organs.  It doesn’t even eat – actually, it cannot eat even if it tried, because it has nonfunctional mouthparts and its gut is filled with nothing but air.  On the other hand, as a naiad, it leads a very active life: swimming, crawling, eating.  At the ripe old bug-age of a year or two, it molts, mates, and dies.

The adult dog-day cicada, like the mayfly, spends most of its life in its nymph stage, except the cicada nymph lives underground, contentedly nibbling on roots for three years.  The periodical cicadas live even longer underground: 13 or 17 years.  When an adult cicada emerges, like the mayfly, it does not have much in terms of defense, which is quite unfortunate for a rather large, bulky, relatively slow-moving bug.  And there are plenty of animals like birds, lizards, small mammals, and even other insects that would love to take advantage of a cicada for an easy meal.  And then there’s the predator that mother cicadas would warn their children about if they could: the dreaded “cicada killer”, a large wasp that will paralyze a cicada, lay eggs in it, and drag it to the wasp’s nest where it will be food for the growing wasp larvae.  But many cicadas do survive, because – like the mayflies – their sheer numbers are just too much for the predators to completely consume.

And what about that lonely Tibicen that showed up at my door, just in time to die?  In spite of that tinge of sorrow I felt when I first saw it on its back, I shouldn’t feel unhappy for it because I know it was at the end of its natural 3-year-long insect life.  I think we have a tendency to misunderstand these creatures because we (and the animals we most closely relate to) spend most of our lives as fully-developed adults, and, for the most part, any stage prior to this is considered to be juvenile, dependent, and relatively brief.  I was thinking about this a couple of days ago as I was walking through a cemetery at St. Luke’s church (ca. 1632) in Smithfield, VA.

A robber fly consuming its prey, a dog-day cicada. Photo: Rob Tilghman. (Many thanks to Professor Charles Holliday of Lafayette College for identifying the robber fly.)

I saw a cicada being consumed by a large robber fly (see picture) on the gravestone of Hilder Owen Winall, who died in 1922 when she was 28 – a full-fledged adult, although definitely still too young, in human terms, to depart this earth.  There were also plenty of graves for people who lived to ripe old ages, like James P. Owen (probably Hilder’s father), who was almost 94 years old when he died in 1953.  But it’s the graves of young children (very commonplace in old cemeteries, unfortunately) that always break my heart, like that of “Little Daisy”, who died in 1901 at the age of 11.  Poor young Daisy.  We can mourn for such a flower who wilted before she finished blooming, a naiad who never was able to experience the trials and tribulations of adulthood.  But we cannot feel sorry for the cicada that fades away in the grasp of the robber fly, because it has lived a long life.  In fact, to say that the cicada is alive only when it is an adult would be like saying a daisy is only alive when it is in bloom.

Photo: Rob Tilghman

[Edit: Shortly after I published this post, Prof. Holliday (who identified the robber fly in the picture above) sent me a picture of another young child's gravestone in Massachusetts.  I think fits well with the theme of this essay: What we may see as a brief existence may in fact be just one stage in a lifetime.]

Another sad gravestone of someone who died too young. Photo by Prof. Chuck Holliday.