OUT WITH THE NIGHT SHIFT
It’s late afternoon. The air is hot and thick, draped like a hazy, wet blanket over the landscape. The dull orange sun hangs heavy over the tops of trees lining the lake and soon drops out of sight. Whirligig beetles drift lazily in the placid water, barely leaving a ripple in their wake. Dragonflies dart back and forth, gobbling up their final meals of midges and other tiny flying insects for the day.
As dusk approaches the throbbing wail of cicadas loses its urgency and eventually stops, as do the relentless attacks of blood-sucking deer flies. The white-throated swifts that had ruled the skies for most of the afternoon are now settled in for the night, giving way to their mammalian counterparts, the bats. Several of these amazing animals skim the lake’s surface right in front of me to drink.
I am in the vicinity of Group Camp 7 in the southernmost reaches of Pocahontas State Park. Accessible only on foot or by horseback, this sylvan oasis within the park definitely has a feel of remoteness seldom experienced so close to a major metropolitan area.
With more than 7,600 acres, Pocahontas is the largest state park in Virginia. Located just 20 miles southwest of downtown Richmond, the park is probably best known for its swimming pool, camping and conference facilities, outdoor performances, and music festivals. But it is also a favorite haunt among local naturalists, especially birders. I have visited the park regularly for the past five years to observe and photograph Virginia insect life during the spring and summer.
As the day shift winds down, the creatures of the night slowly begin to stir, gearing up to take their place on the evening stage. With the arrival of twilight there seems to be a moment or two when all insect life seems to pause briefly, and then the night shift takes over.
The twinkling lights of amorous fireflies begin to appear about the low growth sprinkled along the woodland floor. Neither bugs, nor flies, these soft-bodied insects are actually beetles. Males engage in a slow, looping flight with repeated dips to create a J-pattern with their lights. At the bottom of the descent their abdomen glows bright yellowish-green, becoming dimmer before shutting off completely at the top of their ascent. Their oversized compound eyes are trained on the not-so-distant darkness, hoping to see the light of a female responding with her own perfectly timed and pulsating response amidst the low, herbaceous growth.
Later in the evening another species appears, flying high and fast in the canopy, releasing its light in rapid bursts of three. Fireflies have developed this system of luminous Morse code to locate mates of their own kind among the tangled growth and avoid fruitless encounters with the wrong species.
Chunky June beetles begin to rustle, slowly rising through the air from their daytime hiding places amongst the leaf litter with a buzz. They plow through the night air as if they were trucks in low gear, slowly gaining speed as they begin their nightly search for mates and fresh leaves to eat .
With a headlamp strapped to my sweaty forehead, I venture forth like a bright-eyed Cyclops in search of more of the Commonwealth’s nocturnal insect and spider fauna. The forest floor seems to glitter with tiny stars, which turn out to be the tiny, unblinking eyes of wolf spiders reflecting the beam of my light. They too are searching for insects.
As my headlamp cuts through the ever-growing darkness, moths, beetles, and other airborne insects fly in and out of the sharp beam. Some plummet into my face as they try to reach the light’s source.
For years entomologists have taken advantage of the fact that many insects are attracted to lights at night. Using the ultraviolet component of distant light to orient themselves, many insects are uncontrollably drawn to nearby artificial lights, such as flickering campfires, hissing gas lanterns, brightly lit store fronts, and streetlights. Not the sad, dull yellowish lights that inhabit city streets, but the bright, inviting glow of mercury vapor lights that dot the lesser populated areas of the state.
Lights strong in the ultraviolet spectrum are especially attractive to nocturnal insects. I use several BL black lights specifically for attracting night flying insects. Set in front of and above white sheets for reflectivity and contrast, and powered with 12-volt gel cell battery, the eerie purple glow works like a bug zapper, but without the zap.
Warm, humid, moonless or overcast skies seem to be the best nights to “black light” for insects since there is less ultraviolet light to compete with my set up. The greatest insect activity at lights is right after dark, between 9:30 and 11:00 PM, although some of the larger beetles and moths seldom make an appearance before midnight.
Nocturnal insects can easily maintain a steady flight path in relations to distant sources of light. However, they must fly in ever-tighter spirals in order to maintain their orientation to a nearby light source. Eventually they alight on the sheet or nearby vegetation. If left undisturbed, most would remain within sight of the light until dawn when the rising sun would drive them to seek shelter from the heat and hungry birds.
As night falls, insects swirl about my black light like small comets. My sheet was soon covered in a dizzying array of insects ranging from tiny gnats and beetles just millimeters long, to relatively giant mayflies and June beetles. Dozens of plump, fuzzy moths of all colors settled on the sheet like fighter planes on a flat top. Shiny, smooth and streamlined aquatic beetles emerged from the nearby lake and clambered awkwardly beneath the light, like proverbial fish out of water. Perhaps 200 different species of insects in all made an appearance at the light. The preparation and identification of this relatively small showing would require the full-time efforts of an entomologist for at least a year.
Occasionally a bat hurtled through the cloud of insects, gobbling them up as if they were bellying up to an airborne buffet. Using a series of high-pitched clicks like radar to locate airborne insects, the bats dart and bank sharply through the night air in pursuit of hapless insects.
But not all insects are defenseless against bats. Some moths and mantids have special “ears” capable of picking up signals bats use for their echolocation system. Upon hearing the call of a nearby bat, these insects will take sudden evasive action by pulling in their wings and dropping to the ground or making a spiral power dive to safety.
After 11:00 PM the waves of incoming insects began to slow to a mere trickle. I packed up just after midnight, but the choruses of frogs, katydids, and crickets continued to rise and fall. Although I am sure that they sound like a raucous cacophony to many, I found the chirps, clicks, buzzes, twangs, and bellows to be joyous noise, a perfect sound track for an evening out with the night shift.
©2004, Arthur V. Evans