By: Richard Telford
In 1970, Roger Tory Peterson wrote, “Entomologists fall into two categories: those who find insects endlessly fascinating and those who would get rid of them.” Reflecting the controversy at that time over the indiscriminate use of DDT (for which the U.S. Environmental Protection Agency would subsequently issue a cancellation order in 1972) and other pesticides, Peterson suggested that the latter group of entomologists might “eventually wind up working for chemical companies, devising more sophisticated techniques of annihilation.” The dualism that Peterson notes above, though necessarily oversimplified, is nonetheless reflective of a pattern that extends far beyond the world of entomologists. Insects have a remarkable capacity to evoke in their human observers both fear (largely irrational and unfounded) and wonder (quite rational and well founded). In his ground-breaking books on the insect world, Grassroot Jungles (1937) and Near Horizons (1942), Edwin Way Teale extolled the immeasurable value of the latter response; it required, he argued, only the willingness to slow the pace of our hectic lives long enough to observe a complex and remarkable world we largely overlook.
Few insects offer a more ready source of wonder than dragonflies, which are grouped with damselflies in the order Odonata. The name Odonata is derived from the Greek odonto, meaning tooth—a reflection of their powerful, sharp-toothed mandibles and maxillae, the paired upper and lower jaws that facilitate quick, efficient consumption of prey. Dragonflies, which form the suborder Anisoptera, take prey only in flight, often cupping their six barbed legs in a basket-like shape in order to entrap their target; smaller prey is often consumed without landing. The maxillae contain a pronged inner piece that James G. Needham described in his classic 1929 A Manual of the Dragonflies of North America as “perfectly shaped for a meat fork, used for holding a captured insect and for turning it as the mandibles cut it up.” The deftness of this process is readily apparent when observing a perched dragonfly speedily consume its prey. This is just one of a host of evolutionary adaptions that have shaped the dragonfly into the unrivaled aerial predator of the insect world.
Dragonflies possess four wings, each of which can move independently of the others and can rotate on a forward and backward axis, yielding a supremely dynamic capacity for flight. Dragonflies can fly in all geometric planes. Helicopter-like, they can fly straight up and down or hover in place. They can fly backward and forward, turn abruptly at acute angles, and repeatedly flip their bodies. Harvard Biochemist Stacey Combes, leading a team of researchers who have studied dragonfly flight in a specially built enclosure at the Combes Laboratory in Bedford, Massachusetts, has noted that dragonflies can perform hundreds of such flips while hunting, seemingly without significant exertion. Her team has also documented predation success rates as high as 90 percent in some dragonflies—a truly astonishing figure. Equally astonishing is the speed with which dragonflies engage in these aerial acrobatics. Dragonflies routinely fly at speeds of 15 to 30 miles per hour, with some species flying considerably faster. Credible speed estimates for the Green Darner (Anax junius), for example, range between 35 and 55 miles per hour during straightaway flight. This prompted Edwin Way Teale, in Grassroots Jungle, to title his dragonfly chapter “Winged Bullets.”
One other adaption deserving special note is the dragonfly’s pair of bulbous compound eyes, each of which can contain up to 30,000 ommatidia, or individual lenses, each with its own cornea. The extraordinary perceptive sensitivity of such a structure, in conjunction with the size and placement of the dragonfly’s compound eyes, yields a nearly 360-degree field of vision—a critical adaption that facilitates the flight patterns and the predation success rate outlined above. The dragonfly’s acuity of sight likewise provides a critical defense against predation. Furthermore, while the human eye contains three opsins, or light-sensing proteins, dragonfly eyes can possess up to five. So, while we effectively perceive color through the RGB scale (Red, Blue, Green,) dragonflies can additionally perceive ultraviolet light invisible to humans as well as plane-polarized, or reflected, light. This latter capacity is clearly valuable to a creature that begins its life in water and is destined to return there; both the female and the male return to the water, the former to lay eggs and the latter to protect her during that vulnerable process.
Early this summer, toward dusk, I walked out to the compost pile located at the edge of our yard. Just behind the compost pile, in an overgrown former strawberry garden, I spied a dragonfly suspended by its six legs, wings spread, where it would sleep for the night. Prior to reading Edwin Way Teale’s Journey Into Summer (1960), I had never thought about the sleep of insects. In his book, Teale on a number of occasions notes finding insects at rest at twilight or by flashlight during the night. Teale’s observations of this phenomenon, which had persisted in my mind only in abstract form, took shape before my eyes. The natural world reminds us that there is so much to learn, or at the least so much to which we can pay attention if we choose to do so. I stood long at our compost pile, swarmed by mosquitoes and mesmerized by the beautiful symmetry of this extraordinary creature, which I would later identify as a female Common Whitetail (Plathemis lydia); its stillness at rest contrasted sharply with its swift, deliberate, predatory daytime flight. I hastily fetched a camera and tripod and, with long exposure times, took several photographs.
From that moment, influenced in part by recent time spent reading the correspondence between Rachel Carson and Edwin Way Teale housed at the University of Connecticut’s Dodd Research Center, and in part simply by a sense of wonder and appreciation, I have spent the summer photographing the dragonflies that hunt the cleared half acre of our old farm property. All of the photographs that accompany this writing are the product of that effort. As I do summer chores and projects, I keep near at hand a tripod-mounted camera with macro lens affixed. While I sense that I have seen a greater variety of dragonfly species this summer than I can recall seeing during any of the previous ten summers spent in our 1770 farmhouse, I suspect this is not true. Instead, this perception may simply result from, in Teale’s words, my choice to “pause like [a] stooping giant to peer down into the grassroot jungle at [my] feet.”
Recently, our local state roads have been lined with advertising signs for a regional Mosquito Squad franchise. The signs promise, “No Bugs. No Bites. No Kidding.” It is an unfortunate echo of Roger Tory Peterson’s statement above. Several years ago, Lynne Peeples, writing for the Huffington Post, reported on mounting criticism that Mosquito Squad’s marketing use of a superhero-like cartoon character, Dread Skeeter, targets children and obfuscates both the human health and environmental risks inherent in spraying neurotoxic chemicals for insect control. At a time when pollinating insect populations are suffering catastrophic declines, so much so that the White House just today issued a press release outlining the problem and proposing a course of mitigating actions, we must rethink our relationship with the insect world. A world with no bugs and no bites is likewise a world with no biodiversity, and that is a world in which even the human species cannot survive. In 1937, Edwin Way Teale wrote, “We cannot ignore the insects; we cannot dismiss them as insignificant.” In 1970, Roger Tory Peterson wrote, “[…] insects, because of their astronomical numbers, are undeniably important in our lives. They cannot be ignored.” Still, more than 50 years after the publication of Rachel Carson’s Silent Spring, we struggle to accept the notion that our co-existence with the rest of the natural world cannot be negotiated on our terms alone. Where Dread Skeeter succeeds, dragonflies, which rely principally on mosquitos and small gnats for survival, will vanish, and each loss of this kind precipitates a cascade of other such losses—another lesson that we have been slow to learn.
Recent research on dragonflies has revealed an extraordinary dimension to their hunting. Rather than pursuing its prey, a dragonfly intercepts it, meaning that it must calculate the distance, speed, and direction of its target, adjusting its own speed and direction accordingly. In this context, the predatory success rates of dragonflies documented at the Combes Laboratory are even more impressive. While its superb capacities for flight and vision certainly facilitate this action, it is a complex set of neurological functions that makes such sophisticated targeting possible. This complexity, much of which we do not yet fully understand, should give us pause. According to the fossil record, dragonflies have existed for nearly 300 million years, a fact which can perhaps begin to give us insight on this complexity. Teale argued in 1937 that humans have “lived on earth but a single hour in comparison to the long history of the insects.” The implicit humility of this statement is critical to the long-term preservation of the insect world and of biodiversity itself.