Archive for the Centipedes Category

TRUE CONFESSIONS

Posted in Centipedes, Environment, Musings with tags , , on April 3, 2010 by Dr. Art Evans

By Arthur V. Evans

Every now and again I am asked what is my least favorite insect or spider. I really don’t have an answer for this question. But I can say, without hesitation, that my least favorite arthropod is the centipede.

Don’t get me wrong. I think that centipedes are fascinating animals, but every time I happen upon one of the larger species in the Order Scolopendromorpha, I can feel the hair on the back of my neck stand up and a cold chill run down my spine.

A centipede has never bitten me, so my discomfiture is not based on personal experience. But I do know what the larger species are capable of in terms of delivering a painful, yet non life-threatening bite with their powerful fanglike front feet, or gnathopods. Combined with their speed and lithe bodies, centipedes just set me on edge.

Scolopendra heros from southeastern Arizona dining on a young mouse. Note the thick, black gnathopod next below the head.

Scolopendra heros, the largest centipede species in the United States, measures in at a whopping 6.5 inches (16.5 cm). They range from central and southern Arizona east to southwestern Missouri, Arkansas, and Louisiana. This species is extremely variable in color. During the summer, adults are active around the clock and are easily seen in the headlights of a moving car as they cross the highway at night with their fore bodies bobbing up and down.

I used to collect these big bruisers to put on display in Insect Zoo at the Natural History Museum of Los Angeles County. While on the road, I checked their containers often to make that the lids were securely fastened. My travelling companions were regularly warned that if a lid accidentally came off and a centipede was on the loose, I would immediately abandon the vehicle.

Yesterday, while collecting beetles in the Zuni Pine Barrens of the Blackwater Ecological Preserve, I committed a potentially serious faux pas in the field by peeling back some loose bark of a dead loblolly pine tree that was leaning directly over my head.

Hemiscolopendra marginata occurs in Missouri, Oklahoma, and Texas east to Virginia and Florida; it is absent in most of the Appalachians.

Out of the corner of my eye, I saw a blue-green centipede, Hemiscolopendra marginata, fall from its once-secure perch, its two-inch long body trunk twisting in the air in an effort regain some sort of foothold. Before I could react, it slid across my forearm to the leaf litter below. Or so I thought.

For several seconds my mind raced. What if it didn’t fall on the ground? What if it or another centipede landed on my shoulder? What should I do? What if it got inside my shirt? My now fevered brain began imagining the centipede sinking it’s gnathopods into the soft and sensitive skin of my neck. Or worse.

I stood perfectly still in the bright spring sun filtering through the tall and slender pines, my body tingling all over in anticipation of anything from a crawling sensation to a stabbing pain. The centipede was nowhere to be felt or found. Still, it took me several more minutes to become convinced that my person was centipede-free and begin to feel a sense of relief.

Recounting this event a full day later still gives me the heebie-jeebies!

© 2010, A.V. Evans

HOUSE CENTIPEDES ON THE MOVE

Posted in Centipedes with tags , , on March 21, 2010 by Dr. Art Evans

By Arthur V. Evans

The house centipede, Scutigera coleoptrata, looks more spider and less centipede as it motors up a wall, along a sidewalk, or across the kitchen floor.

One of my favorite non insect arthropod species is a fleet-footed fellow no more that one and a half inches long and has racing stripes down its back. Surrounded by a blur of legs in full stride, the house centipede, Scutigera coleoptrata, looks more spider and less centipede as it motors up a wall, along a sidewalk, or across the kitchen floor.

House centipedes are probably native to the Mediterranean region and have been accidentally transported to many parts of the world. In Tasmania, they are known as the “domestic quickfoot.” These curious animals are well-established across much of the warmer regions of North America, but have managed to penetrate cooler, less hospitable regions in the north by adapting to life indoors.

Outside, house centipedes are at home in the cool, dark, moist recesses of rocks, trees, and leaf litter. They are equally well suited to living in the basements, bathrooms, and drains of our homes, offices, and laboratories. Individuals are sometimes encountered when they become trapped in tubs and sinks, or are attracted to flying insects drawn to porch lights at night.

House centipedes are equipped with a pair of large compound eyes, which allows them to quickly identify potential prey.

Hardwired with a “need for speed” to capture agile prey and escape equally nimble predators, house centipedes possess an array of unique morphological features. The distinct, capsule-shaped head is equipped with a pair of large compound eyes, an exceptional feature among centipedes. Acute vision is probably a major asset when a house centipede must quickly identify a potential prey item while on the run.

The structure of the house centipede’s eyes is similar to those of insects and crustaceans. As a result, they have been the objects of study for scientists seeking to better understand the evolutionary relationships of house centipedes with insects and other arthropods.

House centipedes sprint at speeds of 420mm/second; a 5’8” human would have to run the same distance, relative to their height, at a speed of about 42 miles/hour. But it takes more than the long, slender legs of a sprinter to get these centipedes up to speed; it also requires plenty of oxygen. Their lung-like tracheal system is unique among centipedes and allows oxygen into the body quickly and efficiently to help power the numerous muscles that drive the legs.

Most of their 30 long, slender, banded legs are used not only for getting around and escaping predators, but also to help capture and secure prey. When attacked, the house centipede’s legs easily break off and continue wiggling for a short period, like a lizard’s tail, to distract predators. Fortunately, lost legs are completely regenerated after just one molt. Under ideal conditions, adult house centipedes shed their exoskeletons every 30-60 days for the rest of their lives, which may last up to three years.

Centipedes are the only group of animals that have their front legs modified into fangs that inject venom to subdue and kill prey. Although they usually feed on invertebrates, some larger species will also attack small lizards, snakes, birds, and rodents.

The venom of house centipedes is not particularly toxic, at least not to humans. They seldom bite. Descriptions of the bites of house centipedes range from “minor nuisance” to “severe pain.” However, serious effects from the bite are more likely to be the result of secondary infection than the bite itself.

House centipedes prey on scores of unwanted house pests, especially small spiders, clothes moths, and cockroaches. This one is dining on a crane fly.

Still, house centipedes have become one of those “bread-and-butter” species of the pest control industry. Company literature and web sites would have you believe that these curious and largely beneficial creatures are major household pests. As with many “pests,” the greatest harm involving house centipedes is the “bite” to your wallet caused by the unnecessary purchase of pesticides to control these needlessly maligned animals. The truth is that they do more good than harm because they prey on scores of unwanted house pests, especially small spiders, clothes moths, and cockroaches. And they do all this without charging a dime for their services.

© 2010, A.V. Evans

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