Bug FAQDesert Millipede
Orthoporus ornatus · Order: Spirostreptida · Family: Spirostreptidae
Source: Wikipedia
Desert millipedes are 3 to 9 inches long, dark brown to yellow, and look different in each state. They live in deep, damp desert soils of Arizona, New Mexico, Texas and nearby Mexico, emerging after rains to feed on bacteria and dead plant material. When disturbed they coil up and may release a liquid that irritates skin and eyes.
Source: Wikipedia
How to recognize it
They are dark brownish but can sometimes be yellow. In every state the species looks different.
Source: Wikipedia
Size
Adults average about 4 inches (10 cm) long, but can be as short as 3 inches or as long as 9 inches.
Source: Wikipedia
Is it a pest in the house?
When disturbed they curl up into a ball or coil.
Source: Wikipedia
Does it bite or sting?
If disturbed they may release a toxic liquid from glands along their sides. That liquid can irritate human skin and definitely irritates the eyes.
Source: Wikipedia
Where it lives
They prefer sunny spots but are also seen on rainy summer days. They inhabit deep, damp soil channels and voids in desert ecosystems.
Source: Wikipedia
What it eats
They eat both living and dead organic material.
Source: Wikipedia
Life cycle
They can live more than ten years. They shed their exoskeleton each time they add a new body segment.
Source: Wikipedia
When you see it
They emerge in the early morning after rainy periods when the soil is moist. They come to the surface only once a year; they are not seen feeding above ground year-round.
Source: Wikipedia
Where it comes from
They are found in Arizona, New Mexico, Texas and as far south as San Luis Potosí in Mexico.
Source: Wikipedia
Where it is found in the US
Recorded in 4 of 51 states and DC. Most records: Texas, New Mexico, Arizona, Oklahoma.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
Do desert millipedes bite or sting?
A disturbed one may coil up and release a liquid that can irritate skin and will irritate eyes.
Source: Wikipedia
Same family (Spirostreptidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Orthoporus_ornatus
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-22 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-22.