Wednesday, April 22, 2015

Eastern Hercules Beetle

By Chris Creco  Muhlenberg College Class of 2016

Kelly Geer  CC License Some Rights Reserved



One of my favorite Disney movies is the timeless classic “Hercules.”It tells the story of a Greek War hero—the strongest man who ever lived. He was able to heave boulders, slay ferocious monsters, get the girl, all while staying in tune. Not to be outdone, the Eastern Hercules Beetle (Dynastes tityus) earned its common name for the same reasons. Well, it can’t keep a tune, but it is one of the strongest beetles known to humankind. It is able to lift 850 x its own body weight. Thinking of this in human terms, we would need to be able to lift about 70 tons to match what this beetle can do. To think this very hero which we speak of lives right here in the Lehigh Valley.
The Eastern Hercules Beetle is truly herculean. Adults grow to be over two and a half inches long, making them the largest beetle in North America! This is actually a decrease in size from when it was a baby as some larvae grow to be almost 5 inches long.
A large portion of the Eastern Hercules Beetle body is its long, alien like horns that come off the front of the male’s head. While sometimes used to obtain food, their main function is to act as a sparring weapon to use against other males. They are very territorial insects, and males will often duke it out to see who is the toughest, and also to vie for a female’s attention—think two guys arm wrestling at a bar. A male who can win a fight is more likely to have a female choose him to mate. The other is the size of the horns. The size of the horns are a direct reflection of how large the individual beetle is. Larger beetles invest heavily in making larger horns, while smaller beetles invest heavily in creating larger reproductive structures because they will have less opportunities to reproduce.  A large, aggressive male should have his pick of Eastern Hercules females. 

CC License Some Rights Reserved  Dakota L.
Once a male and female mate, the female will deposit her eggs in a rotting log she finds in the forest. The eggs will hatch and the larva will crawl and develop within the decaying log, feeding and growing for about 18 months before entering their pupal stage. It will emerge as an adult in the spring time, and is active generally at night. During the day you may find the beetle resting/feeding in a compost pile in your yard, but generally you will see them more around your outside lights—specifically if you live near a hardwood forest. This makes it less common to see these beetles around the Lehigh Valley, unless you live in a very unpopulated region.
The Eastern Hercules Beetle is a frequent inhabitant of hardwood forests. While it prefers Ash and Cherry, the beetle is not that picky, and would “rough it” in Oak or Elm if the need arose. It climbs on the trees, preferring to remain in the shade and take advantage of the visual protection that the leaves provide. It’s convenient that the beetle’s number one source for food happens to be the very tree it lives on—picture living in an all you can eat buffet restaurant. It grabs twigs off the tree and quickly whirls them around in its large horns until it finally snaps off of the tree. It then sucks the sap from the twig, and is momentarily satiated. If the beetle happens to be so lucky as to find rotting fruit on the ground, it will happily eat that as well. 
As the name suggests the Eastern Hercules Beetle lives in the Eastern half of the United States—East of the Mississippi river, from New England all the way to Florida. Unfortunately for the Hercules Beetle, in the Northeastern United States, there is an infestation of Emerald Ash Borer’s—insects that eat and subsequently kill the ash tree. Currently, there is no way to prevent the spread of this pest, and the ash tree forests are on the verge of dying out. This is bad news for the Hercules Beetle, whose most beloved habitat and favorite food is the ash tree. It will have to figure out ways to make up for this lost nutrition, or we may not see this beetle in the Lehigh Valley. I guess we would have to change its name to the Achilles Beetle, and the Emerald Ash Borer its Achilles heel.
While looking for food, the beetle must also make sure that it is not leaving itself an easy target for predators. The Eastern Hercules Beetle may be the King Kong of the insect world, but it is the juicy steak of the birds, bats, and small mammals world. Large birds feast on these large insects.  The Coleoptera (Beetles) as a whole have developed a mechanism for avoiding predation, while Eastern Hercules Beetles have developed their own novel way of avoiding being lunch.
 The Hercules Beetles are the largest species of beetle in North America. That only hurts them when they are trying to avoid predators higher up on the food chain. For that, the Eastern Hercules Beetle has developed a system by which it emits an extremely foul smelling odor when being pursued by predators—similar to skunks. It startles and deters the predator long enough for the Beetle to escape, frightened but unharmed.  
Walking through a shady wood on a summer day, one might stumble across these giants of the insect world. Do not be afraid of its aggressive looking body—the Eastern Hercules Beetle is completely harmless. Listen closely enough, and you may be able to hear the “clacking” sound of two males fighting for territory and a female in the distance. Reflect on the marvelous diversity of the Beetle family, and be thankful that these beetles aren’t any larger. Then, maybe, we would have something to worry about. At the very least, we’d have to start wearing helmets more often. 

This post by Chris Greco is licensed under a Creative Commons Attribution 4.0 International License.




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