American playwright David Ives penned a play (Time Flies) about the brevity of life, using mayflies as his allegory. We join the action as two lonely mayflies meet at a pond and really hit it off. As their romance develops, they watch a David Attenborough nature show on TV, and realize they only have a day to live. Some paraphrased snippets:
Him: Swell party, huh?
Her: Yeah. Quite a swarm. Thank you for flying me home.
Him: It’s that late, is it? Anyways, it was nice meeting you. I’m sorry it was May. You don’t, um, live with your parents, do you?
Her: No. My parents died around dawn this morning.
Him: Oh wow, so did mine. . .so, we’re just supposed to meet, mate, have offspring, and DIE?
Her: Yep, that’s what he said.
Him: One bang, a bambino, and boom. . .that’s it?
Her: ‘Fraid so.
Him: Well, I don’t want to die. I say we live!
Her: But how?
Him: We could fly to Paris!
Her: Do we have time to fly to Paris?
Him: Carpe Diem! Ignition, contact, and we’re outta here!
Fleeting. Dissolved by time as if they never existed. A transient burst of energy, a fizz of biological static. Mayflies belong to the order Ephemeroptera, part of ancient group that includes dragonflies and damselflies. Ephemeroptera means “short-lived.” A day in the life of a mayfly really boils existence down to its essentials, an exaggerated metaphor for the rest of us. The implication: once you teach your kids to love, then leave you, your job on earth is done.
Back in the early days of our shared history, humans noticed fish feeding on the surface of lakes and streams. The fish would gorge themselves on insects by breaking the surface of the water, almost within reach of the hungry stalkers. These early fishermen eventually devised a way to catch fish by mimicking the flies they were eating—and fly fishing was born! The first written account of fly fishing doesn’t mention the exact type of bugs being gobbled up, but it does suggest that they were fishing for trout. That means they were probably eating mayflies.
So just how long do mayflies live, anyway? Despite their name, mayflies are active during the warmer months, not just May. Mayflies “hatch” from spring to autumn. The shortest adult lifespan of any mayfly is a specific female (Dolania americana) who lives for less than five minutes. Many species die within hours of their emergence from the water—and this emergence can be remarkable. There can literally be thousands of insects airborne at once. As they swarm, they can form a cloud, obstructing a driver’s vision and making a sunny day seem dark. Homeowners have sat back, mouths agape, and observed their house turn black with
insects. One emergence in 2003 was recorded on Doppler weather radar by the shoreline of Lake Erie. In June 2015, a large swarm of mayflies caused several vehicle accidents on a bridge between Columbia and Wrightsville, Pennsylvania. The bridge had to be closed to traffic twice due to impaired visibility and obstructions posed by piles of dead insects. Speaking of which, there’s an even more offensive downside to a mayfly hatch: the smell of thousands of dead bugs!
There are some 600 mayfly species in North America, being roughly divided into two main tribes. Mayflies from the Mississippi River east have similar traits, but are different from those living in the Rocky Mountain West. While there is some overlap, they tend to be gray, yellow, or brown and have long, thin abdomens. Females deposit their eggs in the water and the larvae spend most of their lives (up to a year) in the water as nymphs. They inhabit nearly all types of water bodies from streams to rivers to lakes. As larvae, populations are often used as a bioindicator species to measure water quality and the health of waterways.
Mayflies are the oldest living group of winged insects, dating back to the Carboniferous Period, about 300 million years ago. As adults, winged mayflies have large compound eyes, short, bristle like antennae, and functionless mouthparts with digestive tracts (for show only—once mayflies enter the winged stages their eating days are over). Their membranous wings include a large, triangular front pair and a much smaller, rounded hind pair (some species don’t have a hind wing set at all). When resting, the wings are held together upright over the body, like a butterfly. Adults have two or three threadlike tails, usually as long as or longer than their body.
Mayflies cycle through different metamorphic changes (instars) just like many other insects do. What is uncommon; however, is that it takes only three transformations for mayflies to reach adulthood vs. four for other insects like butterflies. Mayflies transform from nymph (larva) to adolescent to adult, completely skipping the pupa stage. No matter how short the mayfly’s life, like an iceberg, most of it is lived under water.
Eggs are either dropped at low altitude by dive bombing females or physically deposited in the water; either way, they settle to the bottom or adhere to some submerged object. Most eggs hatch within two weeks, but some have the ability to hold off and exist in a suspended state for a while (i.e., during winter months). This cessation of growth (called diapause) is a highly effective adaptation to avoid hazardous birthing conditions.
After hatching from an aquatic egg, the nymph feeds, grows and develops—some building burrows to live in and feed from while others just cruise around the vegetation looking for snacks. Nymphs feed on waste and plant material, some are carnivorous and feed on other small organisms. They come in many shapes and sizes, all with specialized adaptations of form and function. Some legs are flattened for entering narrow crevices, others for clinging to bottom materials in swift currents, and yet others have long, slender legs and body designed for clambering on submerged plants. Usually, strong swimmers are long and slender. Gills are found on the upper side of their multi-segmented body and may be platelike, feathery, or filamentous—all designed for life under water.
Body proportions of the first nymphal stages are quite different from those of the adult. During
each successive growing stage, the nymph begins to resemble the adult more closely. During this tumultuous time, the mayfly molts (sheds outer skin) anywhere from ten to fifty times—more than almost any other order of insects. The nymph stage can range anywhere from two weeks to two years; however, most nymphs develop within a year. When growth is complete, they rise to the surface of the water and molt into a winged adolescent form, called the subimago.
The subimago then flies from the water to some sheltered resting place (assuming it doesn’t end up in a trout’s tummy) to get ready for its final molt. This period usually lasts overnight, but can also last just a few minutes to several days, depending on species. This is the final costume change which gives rise to the imago, or adult stage. Given that mayflies are such an ancient
group of insects, they do things a little differently than the new-fangled bugs you see in the wild these days. Mayflies are the only insects to molt one more time after developing functional wings. Here’s another one: mayflies have paired genitalia, with the male having two penis-like organs and the female having double hoo-haws. Whoopie!
Mating happens soon after the final molt. Actually, it’s more like a desperate orgy. Swarms of males fly over the surface of the water as dusk approaches, fly up and forward, then float downward on the air currents again. This “invitation” is continued until females join the swarm, and the dance continues in the setting sun. At the right moment, the male approaches the female from below and behind, grasping her thorax with his elongated front legs, and mating is completed on the fly. By this time, of course, their lives are nearly finished, and all this hectic love-making just above the surface of the water also attracts hungry fish. There’s no time for foreplay—it’s gotta be a sure thing (maybe that’s why males have two six shooters?). In most species death comes shortly after mating and egg laying.
So, can mayflies teach us about our own life? To rejoice in life, is it necessary to live a long time? Do we need to always seek gratification, or is it good enough to just be content with life as it is? What’s the lesson? In mayflies is found all the power and sadness of earthly things. They don’t question, “what am I here for?” They are simply part of life. Could it be that we humans are so caught up in our own lives—our hopes and fears—that we cannot see that our function is not to live forever, but to live this moment?
By Larry Gfeller