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UPCOMING OPPORTUNITY:
Join us for another
Winter Hummingbird Expedition to Costa Rica
in November/December 2005 or February 2006

HUMMINGBIRD MORNINGS
Our hummingbird banding demonstrations for
Summer 2005 are now complete.
(Click on the logo at left for details about booking
"Hummingbird Mornings" for your own facility in 2006 or beyond)

GHOSTS AT HILTON POND

The original portion of the old farmhouse at Hilton Pond Center was erected around 1918 by the McFarland family. In decades since, the Faulkners and Bolins and other occupants added to the basic structure. After acquiring the property in 1982, we Hiltons made our own marks on the building, not the least of which was enclosing the back porch to create a glass room that serves as the Center's office and observation area. We suspect "our" farmhouse, which will be a century old in not too many years, would tell many tales if it could talk. In fact, sometimes when we're burning the midnight oil we hear odd noises that--if we were supernaturally inclined--might be interpreted as the house trying to speak. Although we don't really think the old farmhouse is haunted, this week we found ample evidence of a whole gaggle of "ghosts" at Hilton Pond.

All text & photos © Hilton Pond Center

Ghosts are typically thought of as ephemeral things, sometimes caricatured by kids wearing white bed sheets but most often depicted as wispy, transparent spirits, nocturnal in behavior and more or less invisible to the human eye. The latter is a pretty good description of several Hilton Pond "ghosts" we encountered this week around the farmhouse and on the trail--but they showed up in broad daylight.

The first ghost was hanging upside down beneath a Tulip Tree leaf, eerily lit by bright sunlight passing through the blade. In true ghost-like fashion, this particular poltergeist--actually the molted exoskeleton of a Dog-day Cicada nymph (above)--practically glowed from within, its empty eye gazing back at us as we tried to capture its essence with our digital camera. Cicadas, like all insects, have a relatively hard outer covering that can't expand as the occupant grows, hence the need to molt during metamorphosis. As the near-constant buzz in our ear tells us, this August there are plenty of adult cicadas singing in the woods around Hilton Pond. One of them obviously emerged while on the Tulip Tree leaf, leaving behind its ghostly "shell"--complete with wing covers and tiny hair-like structures.

A little further down the path we found another ghost hiding, but instead of a six-legged cicada's shell it was the cast-off armor of an eight-legged spider (above). This particular exoskeleton was stuck to the underside of a leaf at the edge of a web so large it blocked the entire trail--apparently the expansive handiwork of an orb-weaver. Although we couldn't identify the species, we know this particular spider had long, thin legs with brown bands whose pigments were laid down in the exoskeleton and were still visible. Unlike the cicada's rather hard exoskeleton, that of a typical living spider can be relatively soft; in the photo above the outer covering of the soft abdominal segment is shrunken and shriveled.

And speaking of shriveled, our third ghost was a mere shadow of its former self--the pale tan exoskeleton of a Carolina Mantid (right) that floated down from some tree and landed on the deck outside the Center's office. The various native and imported species of praying mantis are skinny insects with narrow abdomens, long mid- and hind legs, and folded forelimbs wickedly adapted for grabbing, skewering, and holding tightly to prey. Like all the rest of its body, the mantid's frontmost legs are covered by exoskeleton that must be molted as the insect grows from one nymphal stage to the next. When we took a close look at the semi-transparent forelegs of the molted mantid (below), we could see an amazing array of serrations and spikes--and it was easy to understand why a mantid's prey seldom gets away once squeezed by those powerful pincers.

The ghostly remains of the cicada, spider, and mantid--all arthropods or "joint-legged" creatures--are similar in origin and make-up. Prior to being shed, each "ghost" was the outermost layer of the living creature, although the exoskeleton--also referred to as the "cuticle"--is non-living. Instead, it is secreted by a single, continuous layer of living cells (the epidermis) and is made partly of chitin, a hard but more or less flexible complex protein similar to human fingernails. Arthropod cuticles can be as much as 60% chitin, or as little at 1-2%. The surface of the cuticle is typically imbedded with some sort of lipid--usually a hard wax--that helps keep living arthropods from losing (or taking in) too much water. This amazing exoskeleton is quite resistant to acids, bases, solvents, rot, and digestive enzymes--which is why an insect mounted on a pin can be kept almost indefinitely in a museum collection, why a cicada "shell" in a protected spot under the eaves may hang unchanged for several years, and why droppings from insectivorous birds and mammals usually contain identifiable chunks of insect exoskeleton.

When a terrestrial arthropod gets ready to molt, the epidermis (or associated glands) secrete a molting fluid that dissolves the inner surface of the old cuticle, beneath which is laid down a softer, expandable exoskeleton. The arthropod then bursts out of its old cuticle--usually through the thorax--after which the animal is very vulnerable for a few hours or days until the new cuticle hardens. While it's still soft, the exoskeleton is typically white--as in the German Cockroach (above left)--so a newly emerged insect or spider often looks REALLY ghostlike until its cuticle finally turns dark.

Yes, there are indeed ghosts at Hilton Pond, although not the type we normally think of at Halloween. Rather than being the haunting, wailing type, our ghosts this week were mere chitinous cuticles left behind by three terrestrial arthropods that had gotten a bit "too big for their britches."

All text & photos © Hilton Pond Center
White cockroach photo © Daniel R. Suiter, Univ. of Georgia