Millipedes in Texas

This article by Jerry Cates, first published on 11 June 2012, was last revised on 28 April 2015. © Bugsinthenews Vol. 13:06(02).

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This article is dedicated to the memory of Dr. Richard Hoffman, a pioneer in the scientific study of the millipedes. I received a sad note this morning (11 June 2012) from Jeff Shultz, of the American Arachnological Society, informing all members of the AAS of the following news:

Richard Hoffman, PhD: Virginia Museum of Natural History

“Dear AAS Member:

It is my sad task to inform you that Dr. Richard Hoffman, Curator Emeritus of the Virginia Museum of Natural History and long-time member of the American Arachnological Society, died yesterday due to complications from a heart attack that he suffered on Friday. Dr. Hoffman is most well-known as a world authority on the systematics of millipeds (Diplopoda), but he contributed substantially to other arthropod groups, including arachnids. In my personal view, Dr. Hoffman epitomized the scientist/naturalist who loved the study of arthropods for its own sake and whose work continues to provide an indispensable empirical foundation for the rest of us to use and to build on. Thank you and farewell, Dr. Hoffman!

Sincerely,

Jeffrey W. Shultz”

Dr. Hoffman’s biography has now (11 June 3012) been posted on a dedicated page of the Virginia Museum of Natural History’s website. Readers may also wish to visit the VMNH home page and review all that the museum — in association with the Smithsonian Institution, in Washington D. C. — does, and, if desired, to donate to that work. Click on this link.

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Now, about those curious, mostly maligned, and often misunderstood organisms known as millipedes…

I have long intended to publish a special article on the millipedes, particularly those found in Texas and the southern U.S. states. These worm-like arthropods are interesting organisms, not only because of their ancient origins, but also for the myriad of ways they impact the daily lives of so many people. Many people refer to them as “worms” and others mistake them for centipedes. It is not unusual for people who find millipedes in their homes or offices to think of them as offensive interlopers that should be sprayed with pesticides to kill them before they can “bite” or “sting” them, or transmit a disease to them. Never mind that millipedes neither bite nor sting, and do not carry diseases affecting humans or our companion pets.

On the one hand, they are annoying. Nobody can deny that. On the other hand, however, they pose no danger to us, and for that reason it makes little or no sense to treat them with pesticides. Most pesticides suggested for millipede control (none of our modern pesticides are considered specifically efficacious, from a practical point of view, for control of millipedes, though many of the synthetic pyrethroids — all of which are known to pose significant complications to humans exposed to them — are often recommended for use in treating their infestations) are well known for their unfavorable effects on humans exposed to them.

Mostly millipedes annoy homeowners and occupants of commercial structures who find them, from time to time, inside their homes or offices. Usually they show up one or two at a time, but sometimes their numbers are so great as to constitute a minor (some would elevate it to a major) invasion. When this happens the homeowner or office worker sees them as small, one-inch or so, light-brown-colored, hard-shelled “worms.” It is difficult enough to keep a house clean with these things littering the carpet, crawling around the house as if they owned the place.

As expected, I am often asked to exterminate these interlopers, using “whatever pesticide it takes to get rid of them, once and for all!” But always, to such requests, my answer is the same: “Millipedes do not bite, sting, or carry diseases that affect humans, so — honestly — you don’t want me to do that. Once you realize that the broad-band pesticides I’d have to use would, besides exposing humans to toxicants they’d best stay away from, destroy many ‘good’ bugs along with these essentially inoffensive critters. Most of those ‘good’ critters are beneficial members of the ecosystem outside your home. When they get killed off, the organisms that replace them tend not to be so beneficial…”

Most of the time, after that brief explanation, the annoyed homeowner or office worker is ready to consider alternatives to pesticides (such as implementing a simple habitat modification program) as a means of controlling the millipedes on their property. But sometimes a more detailed exposition is needed. This article is intended to provide that. The article is in process, and will be enlarged as time permits.

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Taxonomy:

  • Kingdom Animalia — multicellular, eukaryotic organisms whose body plans become fixed during development, some of which undergo additional processes of metamorphosis later in their lives; most are motile, and thus exhibit spontaneous and independent movements; all animals are heterotrophs that feed by ingesting other organisms or their products;
  • Phylum Arthropoda (Linnaeus, 1758) — invertebrate animals with external (exo) skeletons, segmented bodies, and jointed appendages; named using the two Greek words ἄρθρον “AHr-thron” = joint + ποδός “pohd-OHs” = leg; comprised of insects, arachnids, crustaceans, among others;
  • Subphylum Myriapoda (Latrielle, 1802) — arthropods with many legs, i.e., this subphylum was first described in 1802 by the French zoologist Pierre André Latreille (November 29, 1762 – February 6, 1833), a specialist in the arthropods, who used the Greek word μύριος “MY-ree-os” = literally numberless, countless, infinite, and to the Greeks the actual number 10,000, to refer to these animals as arthropods with many legs;
  • Class Diplopoda (De Blainville in Gervais, 1844) — comprised of 13 orders and 115 families, and over 10,000 species;

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Distinguishing Characteristics: in process

Distribution: worldwide. Fossil records show this animal was one of the first terrestrial animals to walk the earth. A miniscule fossil millipede (Pneumodesmus newmani), found on a harbor foreshore near Aberdeen, eastern Scotland, is presently the oldest fossilized millipede found anywhere. Scientists place its age in the vicinity of 420 million years, and under the microscope the fossil reveals holes (spiracles) in the animal’s body that permitted it to breath air, which means only one thing: it lived on land.

Anatomy & Physiology:

Millipedes are myriapods that, with the exception of the legless first segment, and several singly-paired-leg-segments beyond that, otherwise have two pairs of legs on each apparent body segment. Each doubly-paired-leg segment is, in actuality, two segments fused together. The bodies of most millipedes are elongated and cylindrical; some are flattened, dorsally and ventrally; others, known as pill millipedes, are shortened longitudinally and, when threatened, roll into a ball much like the crustacean isopod popularly known as a pillbug. The giant African millipede (Archispirostreptus gigas) reaches a length of 25 cm (15 inches), has a body circumference of as much as 2.5 inches, and lives 5-7 years in captivity. Other species are known to live up to 10 years.

Most species of millipedes have from 36-400 legs. Females of the rare millipede species Illacme plenipes have up to 750 legs on a threadlike body 32 millimeters long and 0.5 millimeters wide; the smaller males of that species have but 300-400 legs, one pair of which serves as organs of copulation. Though until recently not seen since 1928, specimens of Illacme plenipes were rediscovered by Jason Bond and Paul Marek, arachnology professors at East Carolina University, in a ravine in California’s San Benito county.

Feeding & Behavior:

Millipedes are detritivores, and thrive on decaying leaves and other dead plant matter. They secrete moisture onto their food, then debride and masticate the moistened material with their jaws. In greenhouses they become minor garden pests capable of damaging emerging seedlings. Alert gardeners notice the stripping of outer layers of young plant stems, irregular leaf injuries, and damages to plant apices (at the very top of the developing plant), the latter of which is particularly damaging as it prevents the plant from developing further.

Similar Families: in process

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References: In Process

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Questions? Corrections? Comments? e-mail jerry.cates@bugsinthenews.info. You may also register, log in, and leave a detailed comment in the space provided below.




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