Millipedes are common arthropods found in damp environments. They are often mistakenly thought to bite, but unlike centipedes, they do not possess fangs or stingers for defense. The visible reaction upon contact is not a bite but the result of a chemical defense mechanism. This article clarifies what happens when a millipede is handled and how to recognize and treat the resulting skin irritation.
Millipedes Use Chemical Defense Instead of Biting
Millipedes rely on a chemical deterrent when they feel threatened. They protect themselves by secreting a caustic liquid from specialized glands called ozopores located along the sides of their segmented bodies. This expulsion of fluid is their primary defense mechanism.
The defensive fluid is a complex mixture containing irritating compounds, most notably quinones and benzoquinones. Other harsh chemicals, such as hydrogen cyanide and hydrochloric acid, may also be present in small amounts, depending on the millipede species. The purpose of these substances is to create a foul odor and a chemical burn to deter a threat.
Identifying Skin Reactions to Millipede Secretions
The visual result of millipede contact is known as millipede dermatitis or a “millipede burn.” This reaction is localized to the area where the defensive fluid touched the skin, lacking any puncture mark associated with a true bite. The most distinctive feature is a temporary, non-uniform skin discoloration caused by the quinones in the secretion. This staining can appear as a yellowish-brown, reddish, or dark red/black pigment change that may last for days or weeks.
Initial contact often produces an immediate burning or stinging sensation and localized inflammation. In more severe cases, if the fluid is not quickly removed, the affected area may develop a rash, small blisters, or superficial ulceration. The extent of the discoloration and irritation is related to the duration of contact and the potency of the specific species’ secretion. Although uncomfortable, these localized effects are usually self-limiting and do not cause systemic injury in humans.
Immediate Treatment and When to Seek Medical Help
Immediate action is necessary to minimize the skin reaction after contact with the millipede’s defensive fluid. The affected area should be thoroughly washed with soap and water for 15 to 20 minutes to remove all residual secretions. This immediate decontamination helps prevent the chemicals from causing further irritation and deeper staining. For persistent itching or inflammation, a mild over-the-counter topical corticosteroid, such as 1% hydrocortisone cream, can be applied.
Medical attention becomes necessary if symptoms escalate beyond a localized skin reaction. Seek urgent care if the secretions contact the eyes, which requires immediate and prolonged rinsing followed by ophthalmologic evaluation due to the risk of corneal injury. Professional help is also warranted if signs of a severe allergic reaction develop, including facial swelling, difficulty breathing, or a rapid heart rate. If the irritation, pain, or discoloration does not begin to resolve within a few days of home treatment, consulting a healthcare provider is advised.