The woodlouse spider, scientifically known as Dysdera crocata, is a common arachnid found worldwide. It is often encountered in damp, dark environments. This spider has a distinctive appearance with a reddish-brown body and prominent, forward-pointing fangs.
Understanding Woodlouse Spider Bites
Woodlouse spiders are venomous, not poisonous. The distinction is important: venom is injected through a bite or sting, while poison is ingested or absorbed. Like most spiders, Dysdera crocata produces venom to subdue its prey, primarily woodlice (roly-polies or sowbugs). Its large fangs are adapted to pierce the tough exoskeletons of these crustaceans.
While these fangs can penetrate human skin, the venom is generally not considered medically significant to humans. Bites typically cause minor pain, primarily due to the mechanical puncture, and this pain usually lasts less than an hour. Common symptoms include localized pain, redness, swelling, and itching at the bite site. These reactions are usually mild and often compared to a bee or wasp sting. Severe reactions are rare, as the venom is not potent enough to cause significant harm to humans or pets.
Identifying Woodlouse Spiders
Woodlouse spiders have several distinct physical characteristics. They typically have a tawny orange to dark-red cephalothorax (fused head and thorax) and legs of the same reddish-brown hue. Their abdomen contrasts with a shiny, pale beige to yellowish-brown or grayish-white color. Adult females usually measure between 11–15 millimeters (0.43 to 0.59 inches) in body length, while males are slightly smaller, around 9–10 millimeters (0.35 to 0.39 inches).
Their most recognizable feature is disproportionately large, forward-pointing fangs (chelicerae). These prominent fangs are easily visible and specialized for their diet. Unlike most spiders, woodlouse spiders possess six eyes, often arranged in a compact cluster or two rows. They do not spin webs for hunting, instead actively foraging at night. They prefer damp, dark environments such as under logs, rocks, leaf litter, and sometimes inside basements or other humid areas of homes.
What to Do After a Woodlouse Spider Bite
If bitten by a woodlouse spider, clean the affected area with mild soap and water. Apply a cool compress (e.g., a damp cloth or ice pack) for about 15 minutes each hour to reduce pain and swelling. If the bite is on an arm or leg, elevating the affected area can also be beneficial.
Over-the-counter pain relievers, like ibuprofen, can manage discomfort. While bites are generally mild, seek medical attention if symptoms worsen, signs of infection appear (increasing redness, warmth, pus, or spreading pain), or if you suspect an allergic reaction. Such reactions are uncommon but require professional medical evaluation.