Common Name: Desert Millipede

Scientific Name: Orthoporus ornatus

Size: Can attain a total length of 5+ inches (18+ cm)

Description:

Desert Millipedes are a cylindrically-shaped arthropod in the Class Diplopoda. There class name refers to the fact that these interesting organisms have two pairs of legs per body segment. Coloration can range from a light tan to a dark brown. Some individuals are an orange or a burnt orange color and these can be beautiful.

Behavior:

Millipedes are usually active in the late evening and at night. During periods of heavy rainfall, these animals may come out during the mid-day. In some areas of their range, their population density can be extremely high, making them one of the most commonly encountered invertebrates. During drought conditions, surface activity is severely curtailed. Adults overwinter and become active during the spring (Drees and Jackman, 1998). Young are born during the spring and after approximately 21 to 25 weeks (and seven instars) develop into the adults. During this period, they continue to add leg-bearing body segments (Drees and Jackman, 1998). Millipedes move with a wave-like motion of their legs. When they are threatened, millipedes curl into a tight spiral and emit a noxious fluid from their repugnatorial glands at the base of their legs. This fluid can cause a reaction in people who are allergic, but for the most part is not harmful to man. It will, however, kill other invertebrates, depending on species (Wauer, 1973).

An interesting side note is the fact that there is a larval beetle known as a millipede-killer that specializes on feeding on millipedes. We have observed several of these larvae in the wild including one actually feeding on a millipede. These beetle larvae bore into the side of the body of the millipede and suck out the fluids. All that remains after the larvae is done is the empty shell of the millipede!

Habitat: Desert Millipedes are widespread throughout West Texas, Southern New Mexico, and Southeastern Arizona. There are several species of millipedes found in this region. They live in both dry regions and the higher elevation grasslands. We have observed hundreds of these animals during late spring and early summer in Val Verde, Terrell, Brewster, and Presidio Counties. These organisms can live in the desert because they only come to the surface when conditions are such that they do not desiccate. We hardly ever observe these animals during periods of high temperatures and low humidities. We have seen them out during periods of rainfall; in fact, we have observed numerous individuals drinking water during periods of rain.

Prey

Millipedes usually scavenge on decaying organic material and occasionally feed on live plants (Drees and Jackman, 1998). We have observed numerous individuals feeding on DOR (dead-on-road) animals including run over millipedes.

Captive Care

Millipedes are extremely interesting captives and do well in captivity if provided with a few simple requirements. They must be kept moist but not too wet. This is because they prone to desiccation. We have successfully maintained several individuals together in a five-gallon aquarium with a mixture of sand and vermiculite as the substrate. This substrate works well because it is easy to keep moist. To keep the substrate moist, simply mist the cage several times weekly. Because they do well at lower temperatures, we kept our millipedes at room temperatures. During the winter, the temperatures would drop to 65 °F (19 °C); during the summer, the temperatures would occasionally reach 80 °F (26 °C). At this temperature regime, the animals would fed year-round, although they would not eat as much during the winter. We feed our millipedes red-leaf lettuce, romaine lettuce, and kale. On this regimen, we have been able to keep our millipedes alive for almost two years before they perished. These animals were all adults when we collected them.

Special thanks to Barney Tomberlin for doing the initial editing on this article.

References:

Drees, Bastiaan M. and John A. Jackman. 1998. A Field Guide to Common Texas Insects. Gulf Publishing Company. Houston, Texas. 359 pp.

Wauer, Roland. 1973. Naturalist’s Big Bend. Peregrine Productions. Santa Fe, New Mexico. 160 pp.