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Millipedes are among the oldest — and most fascinating — decomposers. They’re found in almost all areas of the world.

Often mistaken for worms, these small arthropods were among the first animals to evolve from water to land habitats. In fact, one millipede fossil found in Scotland is estimated to be 428 million years old!

Despite their fascinating nature, not everyone is a fan of the millipede. While these burrowing creatures aren’t poisonous to humans, it’s possible to be allergic to them.

If you’re curious about whether it’s safe to be around millipedes, keep reading to learn more about their nature and how they interact with humans.

While millipedes defend themselves like other animals, they don’t bite. Instead, millipedes can coil up into a ball when they feel threatened.

In some instances, they can emit a fluid toxin from their glands to fight against predators such as:

  • spiders
  • ants
  • other insects

Some millipedes can spray toxin a couple of feet away if they detect a threat.

The toxin from the millipede’s glands is primarily made up of hydrochloric acid and hydrogen cyanide. These two substances, respectively, have a burning and asphyxiation effect on the millipede’s predators.

In large quantities, the toxin is harmful to humans, too. However, the quantity millipedes emit is so small that it can’t poison people.

Aside from predators, humans can also come into contact with this toxin.

For example, if you were to pick up a millipede that has coiled in defense, you might notice a brownish tint to your skin after you put the millipede back down.

You can wash the liquid off your hands, but it still might stain temporarily.

While the liquid millipedes emit isn’t toxic to humans, it’s possible to have skin irritation or even be allergic to it. If you’re allergic to millipedes, you might notice the following symptoms after handling them:

  • blisters or hives
  • redness
  • rash
  • itchiness and/or burning

Millipede toxin can cause blisters and burns. Wash your skin right away, even if you don’t think a millipede has emitted any liquid onto your skin. This can help prevent a possible allergic reaction.

If you develop blisters as a result of handling millipedes, wash your skin with lukewarm water and regular soap. Aloe vera gel can also help soothe the blisters.

Over-the-counter antihistamine such as Benadryl may help with an itchy rash. You may also treat the rash with a soothing topical, such as oatmeal lotion or hydrocortisone cream.

Be careful not to rub your eyes after handling millipedes. The arthropod’s toxins can lead to conjunctivitis and other uncomfortable eye issues.

Wash your hands thoroughly after handling them, even if you don’t think you’re allergic or have any other type of reaction to millipedes.

Severe allergic reactions are rare

A millipede allergic reaction is rarely life-threatening. However, you should seek emergency medical care if you experience any of the following symptoms of a severe allergic reaction:

  • facial swelling
  • breathing difficulties
  • rapid heart rate
  • widespread rash
  • unconsciousness

Certain species of centipedes may be much longer than millipedes, and vice versa. Centipedes are flatter in appearance and can resemble small snakes with legs, rather than the harmless worms that millipedes look like.

Centipedes have one pair of legs per body segment, compared to the two pairs per segment millipedes have. The legs of a centipede are also longer, as are their antennae.

Unlike millipedes, centipedes can bite humans when they feel threatened. It’s said to feel like a bad insect sting. The symptoms can last for a few days or longer in more severe cases.

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The millipede is near the pink circle. The centipede is below, near the yellow circle.

Millipede habitats tend to be dark and damp. They prefer to hide in soil or under debris, such as:

  • leaves
  • rotting wood
  • mulch

These arthropods can be found around the world, with the largest and most allergenic versions found in tropical regions such as:

  • the Caribbean
  • South Pacific

As a general rule of thumb, the larger the species of millipede, the more likely its toxins will cause harm to your skin. The larger species emit higher levels of toxins to its predators.

Millipedes are naturally drawn to damp areas. They also like to hide underneath debris, such as leaf piles.

Sometimes millipedes will come into homes looking for moisture. You might find them in damp areas such as first-floor laundry rooms and basements.

While they won’t bite or cause any other kind of bodily harm, millipedes can become a nuisance if they reproduce and decide to turn your home into their own.

Millipedes will die off quickly without moisture. Keeping your home dry is one way to detract against these creatures. You can also help keep millipedes out of your home by:

  • making sure weather stripping is intact around doors
  • sealing off window edges
  • caulking openings
  • sealing any holes or openings in the home’s foundation
  • fixing any plumbing leaks

To date, there are over 12,000 known living species of millipedes worldwide.

None of these are documented to be poisonous to humans. A millipede also won’t bite you, but the toxins of some species can cause skin symptoms when you handle them.

Still, as with handling any animals, it’s important to take extra care.

Allergic or irritant reactions are possible, especially if you come into contact with a millipede that emits toxins from its glands as a natural defense mechanism.

See your doctor if any symptoms of an irritant or allergic reaction don’t clear up with home care.