The Woodlouse Spider, scientifically known as Dysdera crocata, is a fascinating arachnid frequently encountered in residential areas across the globe. This species is often feared due to its striking appearance and large fangs. While its bite can cause discomfort, the Woodlouse Spider is generally considered medically insignificant to humans.
Identifying the Woodlouse Spider
The appearance of Dysdera crocata is distinct, making it relatively easy to identify when seen up close. Its body exhibits a pronounced two-tone coloration, featuring a smooth, reddish-brown cephalothorax (head and chest region). This contrasts sharply with its abdomen, which is a pale gray, tan, or sometimes yellowish hue.
One of the most characteristic features of this spider is its disproportionately large chelicerae, or fangs, which project forward from the front of its head. These fangs are powerful and adapted to penetrate the tough, armored exoskeletons of its preferred prey. Unlike many spiders that possess eight eyes, the Woodlouse Spider has only six eyes, typically arranged in a tight, compact semi-circle or oval formation on the front of the cephalothorax. The body length of an adult typically ranges from about 10 to 15 millimeters, with the females usually being slightly larger than the males.
Assessing the Threat: Bite Severity and Symptoms
The Woodlouse Spider is not an aggressive species and will only bite defensively if it is accidentally trapped or directly handled. The large fangs, designed to pierce the tough shell of a woodlouse, can easily puncture human skin if the spider feels threatened. The bite is often described as feeling like a sharp pinprick or a bee sting due to the mechanical action of the large chelicerae.
The venom of Dysdera crocata is mild and non-necrotic, meaning it does not cause tissue death. Symptoms resulting from a bite are typically localized and short-lived, resolving within a few hours or days without medical intervention. The immediate reaction usually includes localized pain, mild redness, and some swelling at the site of the puncture.
Some individuals may also experience localized itching or a slight burning sensation in the area surrounding the bite. Since the symptoms are mild, treatment focuses on basic wound care to prevent secondary infection. It is advisable to clean the bite site thoroughly with soap and water as soon as possible. Applying a cold compress or an ice pack wrapped in a cloth to the affected area can help minimize swelling and reduce discomfort. Over-the-counter pain relievers can be used if the localized pain is persistent. Anyone experiencing symptoms beyond localized discomfort, such as signs of a severe allergic reaction, should seek medical attention immediately.
Natural Behavior and Habitat
The common name of this spider directly relates to its diet, as its primary food source consists of woodlice, also known as pill bugs or roly-polies. Because its prey is nocturnal, the Woodlouse Spider is also most active after sunset, seeking out woodlice in the dark.
These spiders prefer habitats that are consistently damp and sheltered, which is where their prey is commonly found. Outside, they live under rocks, logs, loose bark, and leaf litter, utilizing these spaces for protection during the daylight hours. They do not spin webs for catching prey, instead relying on active hunting to find and capture woodlice.
Encounters with Dysdera crocata indoors are usually accidental, often occurring when the spiders wander in seeking shelter or following their prey. They are frequently found in basements, laundry rooms, or ground-level garages where conditions are cooler and slightly more humid.