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GIANT STAG BEETLE:
OUCH!

All text & photos © Hilton Pond Center

We've commented before about the non-selective nature of mist nets we unfurl to catch birds around Hilton Pond and how we sometimes capture other aerial animals such as bats and butterflies. We were a bit surprised this week, however, when in broad daylight we snared a creature more likely to be seen flying around a porch light at night. Fortunately, we observed this big beetle hit the net and hurried to get it BEFORE it had opportunity to become tightly enmeshed; unfortunately, the beetle was therefore free enough to twist and turn and use its gigantic, inch-long, sharply pointed mandibles (above) to clamp down on a sensitive fingertip. OUCH! We'd rather be nipped by a cardinal.

The Giant Stag Beetle, Lucanus elaphus, is a relatively uncommon resident of the southeastern U.S. as far west as Oklahoma. Its technical name comes appropriately from two Greek words for a kind of beetle and a male deer (or stag) that has antlers shaped like the enlarged mouthparts of the male Giant Stag Beetle. (Incidentally, this insect is sometimes incorrectly called "Elephant Beetle" when people misinterpret its species name.) Like deer, male Giant Stag Beetles battle each other with their "antlers," grasping and flipping opponents until the victor gets to mate with a nearby female (right) who is adorned by much, much smaller mandibles. (Despite the tininess of her mouthparts, the female can still pinch and--we can report from memorable experience--will do so if given half a chance.) Overall, a male Giant Stag Beetle can be a little more than 2" long--half its length is mandibles--while the female is only about 1.5" long and with a head narrower than her thorax. Individuals vary in color from chestnut brown to brownish-black, with the male's head and mandibles being somewhat paler than the rest of his exoskeleton.

After mating the female Giant Stag Beetle chooses a hardwood snag or stump in which to lay her eggs; this site provides a food-rich home for her larvae for at least 12 months, possibly for multiple years. The white, red-headed grub (left)--which molts through several stages and eventually reaches a length of two inches or so--consumes fungus-enriched, carbohydrate-laden dead wood that is, in turn, digested by symbiotic bacteria and other microbes in its gut. (Dead microbes provide a good source of fats and proteins the grub needs to grow and metamorphose.) Stag beetle larvae--which sometimes occur in large colonies in a particularly rich rotten-wood locale--are true decomposers and do no damage to living trees.

Eventually the grub forms a non-feeding pupal stage, with adults emerging in late May and June; they seek mates and dine on sugary liquids such as fruit juice, tree sap, or aphid honeydew. Despite his impressive toothed mandibles (above), the male is unable to use his other mouthparts to chew--nor is the female. Perhaps because their diet is energy-rich but completely lacking in protein and fat, adults die in about a month.

As members of the Stag Beetle Family (Lucanidae), Giant Stag Beetles can be distinguished from other large beetles by examining their paired antennae (see two photos just above). In lucanids these structures are distinctly elbowed and the four terminal oval-shaped segments are separated and inflexible; they do not fold together as in Scarab Beetles.

All text & photos © Hilton Pond Center

One reason a Giant Stag Beetle can make a mess of a mist net is because its antennae, huge mandibles, wing covers, and legs all get caught on strands of mesh. And, since it has six of the latter, that's a lot of appendages flapping around getting snared. While we had our macro lens set up to photograph the beetle's antennae we decided to look at its legs and found each was tipped by an impressive pair of tarsal claws (above)--curved just right to capture net strands. Enhancing its ability to get caught were the beetle's "empodia," tiny forked structures that lie behind and between the tarsal claws. Again from past experience at Hilton Pond Center, we know male Giant Stag Beetles can cling to mist nets AND to human skin with decurved tarsal claws--all the better to grab hold of a bird bander's fingertips with their mighty antler-like mouthparts.

Did we say OUCH?

All text & photos © Hilton Pond Center

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Be sure to scroll down for an account of all
birds banded or recaptured during the period,
plus other nature notes of interest.

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