How to Identify Household Myriapods

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Centipedes and millipedes are arthropods belonging to the subphlyum Myriapoda. They occasionally enter homes in search of shelter, moisture, and food. While these many-legged critters are not harmful to humans, their appearance can be unsettling.


House centipedes don’t cause damage to belongings or stored food, nor do they attack people or pets (although they may bite in self-defense in rare cases).

In fact, they are considered mostly beneficial because they only hunt other pests like cockroaches, spiders, and ants.

House centipedes are seldom seen because they are nocturnal and are quick to flee when people are around. They usually enter homes during the winter and hide out in cool, dark, and humid areas in basements and bathrooms.

Size: 1″ – 1 3/8″ long (25 – 35 mm); appears 3″ – 4″ long if including legs and antennae

Color: Yellowish-gray or light brown

Shape: Elongated, flattened body with slender antennae and 15 pairs of long legs

  • 15 pairs of long legs with light and dark stripes (one pair of legs per body segment)
  • Long, slender antennae approximately twice the length of its body
  • Flat head with well-developed eyes, jaw-like mandibles, and modified pincer-like legs (forcipules)
  • Elongated, flattened body divided into 15 segments
  • 3 dark stripes running longitudinally down the back

Greenhouse millipedes are usually found outdoors in moist, shady locations like gardens, flower beds, and compost piles.

They’re most commonly seen in the summer when it’s hot and dry, forcing them to enter homes in search of moisture. Heavy rainfall can also prompt them to seek shelter indoors. Once inside, they tend to invade cool, dark areas like basements and crawl spaces.

These millipedes are harmless to humans, although they release a foul-smelling odor when alarmed.

Size: 3/4″ – 7/8″ long (19 – 22 mm)

Color: Light to dark brown

Shape: Long, cylindrical body with short antennae and many pairs of short legs