Centipedes are predatory arthropods (class Chilopoda) recognizable by their elongated, segmented bodies and a single pair of legs per segment. All centipede species possess venom, which they inject using specialized appendages to subdue prey. While they inject this venom if threatened, the overall risk they pose to human health is generally considered low. For most people, a defensive encounter results in a painful, but temporary, localized injury.
How Centipedes Attack
Centipedes do not bite with mandibles; instead, they inject venom using pincer-like appendages called forcipules. These forcipules are modified first legs located behind the head, which they use to grasp and pierce the skin. The venom is delivered through a duct system running from a gland within the forcipule to its sharp, clawed tip.
When a centipede strikes, the forcipules leave two distinct puncture marks, often forming a chevron or V-shape. The venom is a complex cocktail designed to rapidly immobilize prey, containing a diverse mix of proteins and peptides. Specific compounds like histamine, serotonin, and various enzymes contribute to the immediate pain felt upon envenomation. This chemical action focuses on disrupting the prey’s physiological systems.
Reactions to a Centipede Bite
The most common reaction to centipede envenomation is intense, localized pain at the injection site, often comparable to a bee sting. This is quickly followed by local symptoms such as redness (erythema) and swelling (edema) around the puncture marks. Many individuals report tingling, numbness, or a burning feeling that can last for several hours. These reactions are confined to the strike area and usually subside completely within 48 hours.
In rare instances, the venom can cause systemic effects extending beyond the injury area. These less common reactions may include generalized symptoms like headache, nausea, mild fever, or temporary swelling of nearby lymph nodes. An allergic response to the venom is the most serious potential outcome, though it is uncommon. Signs of a severe allergic reaction, such as difficulty breathing, generalized hives, or a rapid heart rate, require immediate medical attention.
Comparing Common and Dangerous Species
The size and species of the centipede directly correlate with the severity of the envenomation, based on the volume and potency of the venom delivered. The common house centipede (Scutigera coleoptrata), frequently found in homes, is small and possesses forcipules often too weak or short to penetrate human skin. If it manages to strike, the resulting pain is typically mild and short-lived, similar to a minor insect sting.
Conversely, the largest centipedes, such as the Scolopendra species found in tropical and desert regions, cause the most painful human encounters. Species like the Giant Desert Centipede (Scolopendra heros) or the Vietnamese Giant Centipede (Scolopendra subspinipes) can reach lengths of eight to ten inches. Their substantial size allows them to deliver a larger volume of chemically potent venom, resulting in prolonged pain and pronounced swelling. Bites from these larger centipedes are associated with rare, severe systemic effects.
Immediate Care for a Centipede Bite
For most centipede strikes, simple first aid measures effectively manage pain and localized swelling. First, thoroughly clean the injury area with soap and water to minimize the risk of secondary infection. Applying a cold compress or an ice pack wrapped in cloth helps reduce pain and inflammation; apply this for alternating ten-minute intervals.
Over-the-counter pain relievers, such as acetaminophen or ibuprofen, manage discomfort, while oral antihistamines may help reduce swelling and itching. Seek professional medical attention if symptoms worsen, if signs of infection develop (such as red streaking or discharge), or if localized symptoms persist past 48 hours. Any indication of a severe allergic reaction, including throat swelling or breathing difficulty, warrants emergency medical services.