Tuesday, September 07, 2010

LIfe and Death in the Swamp

At the Audubon Center at Francis Beidler Forest, there were several examples of life's circular movement.  The discovery of a Polyphemus Moth (Antheraea plolyphemus) caterpillar along the boardwalk's handrail was matched with yesterday's photographs of adult Polyphemus Moths.  Although caterpillars dine on a variety of trees, including dogwoods, elms, hickories, maples, oaks and willows, the adults do not eat.  Once the adults emerge, males and females spend their first day finding each other.  Females emit pheromones, which a male can detect miles away.  Once mating has occurred, the female will spend the rest of her life laying eggs.  Adults only live for a few days.

We were not on the boardwalk hunting caterpillars.  The odor of death had been detected near the boardwalk at #112 and the remains of a deer could be seen ten meters to the north.

Upon closer inspection, we saw that what at a distance looked like gray fur was actually a living, writhing mass of maggots.  The maggots are likely from the genus Lucilia, which contains species like the Green Bottle Fly (Lucilia sericata), although American Carrion Beetles (Necrophila americana ) were also on the scene.  These flies can be found around the world and they specialize in laying eggs in and eating dead or decaying flesh, often within hours of the organism's death.  The larvae transition through three instars on a predictable schedule based on the temperature of the environment and amount of disturbance.  Therefore, these insects are used by forensic scientists to estimate the time of death of a corpse and whether or not the corpse was disturbed.

When the images of the maggots were taken, they covered the majority of the fawn's body and could be easily heard as they moved and ate.  There was little left for any larger scavengers.  However, that did not prevent the vultures, both black and turkey, from finding the carrion two hours later below the forest's thick canopy.  The vultures' stay was brief due to the lack of suitably-sized portions.  During their inspection, the vultures did move the deer's remains and dislodged many of the maggots.

No word yet on whether the maggots separated from the carcass were able to reestablish contact with their meal.

Images by Mark Musselman

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