What poison do millipedes secrete?
Millipedes are worm-like bugs. Certain types of millipedes release a harmful substance (toxin) all over their body if they are threatened or if you handle them roughly. Unlike centipedes, millipedes do not bite or sting.
The toxin that millipedes release keeps away most predators. Some large millipede species can spray these toxins as far as 32 inches (80 cm). Contact with these secretions may cause allergic reactions in some people.
This article is for information only. DO NOT use it to treat or manage an actual toxin exposure. If you or someone you are with has an exposure, call the local emergency number (such as 911), or the local poison control center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States.
The harmful chemicals in millipede toxin are:
- Hydrochloric acid
- Hydrogen cyanide
- Organic acids
- Hydroquinones (in some millipedes)
Millipede toxin contains these chemicals.
If the millipede toxin gets on the skin, symptoms may include:
- Staining (skin turns brown)
- Intense burning or itching
If the millipede toxin gets in the eyes, symptoms may include:
- Blindness (rare)
- Inflammation of the membrane lining the eyelids (conjunctivitis)
- Inflammation of the cornea (keratitis)
- Spasm of the eyelids
Nausea and vomiting may occur if you come into contact with a large number of millipedes and their toxins.
Wash the exposed area with plenty of soap and water. Do not use alcohol to wash the area. Wash eyes with plenty of water (for at least 20 minutes) if any toxin gets in them. Get medical attention right away. Tell the health care provider if any toxin got in the eyes.
Before Calling Emergency
Have this information ready:
- The person’s age, weight, and condition
- The type of millipede, if known
- The time the person was exposed to the toxin
Your local poison control center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States. This national hotline will let you talk to experts in poisoning. They will give you further instructions.
This is a free and confidential service. All local poison control centers in the United States use this national number. You should call if you have any questions about poisoning or poison prevention. It does NOT need to be an emergency. You can call for any reason, 24 hours a day, 7 days a week.
What to Expect at the Emergency Room
If possible, bring the millipede to the emergency room for identification.
The provider will measure and monitor the person’s vital signs, including temperature, pulse, breathing rate, and blood pressure. Symptoms will be treated.
Most symptoms often go away within 24 hours after exposure. A brownish discoloration of the skin may persist for months. Severe reactions are mainly seen from contact with tropical species of millipedes. The outlook may be more serious if the toxin gets in the eyes. Open blisters may become infected and require antibiotics.
Erickson TB, Marquez A. Arthropod envenomation and parasitism. In: Auerbach PS, Cushing TA, Harris NS, eds. Auerbach’s Wilderness Medicine. 7th ed. Philadelphia, PA: Elsevier; 2017:chap 41.
James WD, Elston DM, McMahon PJ. Parasitic infestations, stings, and bites. In: James WD, Elston DM, McMahon PJ, eds. Andrews’ Diseases of the Skin Clinical Atlas. 11th ed. Philadelphia, PA: Elsevier; 2018:chap 20.
Seifert SA, Dart R, White J. Envenomation, bites, and stings. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 104.
Review Date 11/13/2021
Updated by: Jesse Borke, MD, CPE, FAAEM, FACEP, Attending Physician at Kaiser Permanente, Orange County, CA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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Question How are millipedes and centipedes alike and how do they differ?
While both millipedes and centipedes belong to the phylum Arthropoda and to the subphylum Myriapoda, millipedes belong to the class Diplopoda and centipedes belong to the class Chilopoda. Read on to discover additional ways in which millipedes and centipedes are alike or different.
Some of the ways in which millipedes and centipedes are alike include:
- They are both invertebrates (without backbones) and belong to the largest phylum in the Animal Kingdom which also includes insects, spiders, crabs, lobsters, etc.
- They both have one pair of antennae, many pairs of legs, and breathe through little holes or spiracles on the sides of their bodies.
- They both have segmented bodies, poor vision, external skeletons and jointed legs.
- They grow by moulting or shedding their external skeletons and, when young, grow new segments and legs each time they moult.
- They are both found throughout the world, but are most abundant in the tropics.
- They require a moist environment and are most active at night.
Some of the ways in which millipedes and centipedes differ from each other include:
- Millipedes have two pairs of short legs on each body segment, a rounded body, and a hard external skeleton. Their legs are tucked under the body and difficult to see. The number of body segments varies with the species (estimated in the range of 10,000 species), but the number of pairs of legs generally ranges between 40 and 400. The females of a nearly extinct species of California millipede have up to 750 legs.
- Centipedes have only one pair of legs on each body segment; these are easily spotted sticking out from their flattened bodies. The number of body segments varies with the species (estimated in the range of 8,000 species), and the pairs of legs vary from 15-177, plus or minus one. Centipedes have an odd number of pairs of legs; the last pair trails behind the body.
- Millipedes have short antennae and move in slow waves, burrowing and eating their way through moist leaf clutter, fungi, and decayed plant material on the ground. As they plow through the soil, munching on dead plants and other vegetation, they aerate and enrich the soil, much like earthworms.
- Centipedes have long antennae and their back legs are nearly as long as their antennae. The antennae help them locate their prey, and their first pair of legs, modified into venomous claws, help them capture and paralyze their prey. Centipedes eat spiders, insects, worms, and other arthropods. The Amazonian giant centipede is over twelve inches in length and is said to eat frogs, mice, and lizards.
- Millipedes are attacked by shrews, toads, birds, and badgers. When attacked, millipedes curl their bodies into tight spirals to protect their soft undersides. This coil shape also protects their heads and legs. They sometimes burrow to bury themselves when disturbed, using their front legs to push away the soil. Many species of millipedes have defense glands (called ozopores) which discharge a smelly and disgusting-tasting liquid that drives off many predators. This liquid contains a variety of irritants including hydrochloric acid, phenol, and irritating quinones.
- Centipedes are attacked by lizards, scorpions, and birds. Centipedes are flexible, fast, and toxic. They use both their long back legs and antennae in escaping predators, speedily scuttling away between cracks in rocks, litter, and logs. Centipedes can quickly move backwards and sideways if necessary. In addition to poisoning animals with their venomous bite, centipedes can use their long back legs to squeeze a predator. Their venom includes several substances including histamines, serotonin, and cardio-toxins. Centipedes can also, like some insects, crabs, and lobsters, simply “drop” legs held by a predator and run away on their remaining legs.
Published: 11/19/2019. Author: Science Reference Section, Library of Congress
- Diplopoda External (Encyclopedia of Life, Smithsonian Institution)
- Chilopoda External (Encyclopedia of Life, Smithsonian Institution)
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