Woodlouse Spider

The woodlouse spider is a distinctive ground-dwelling species easily recognized by the sharp contrast between its glossy reddish-orange cephalothorax and legs and its pale, unmarked grayish abdomen. It is best known for its highly specialized diet: this spider is one of the few predators equipped to regularly overcome the armored exoskeleton of woodlice, also known as pillbugs or sowbugs, using unusually large, elongated chelicerae (fangs) that can pierce their prey's tough shell.

Originally native to the Mediterranean region, the woodlouse spider has been introduced widely and is now established across much of Europe and North America, closely tracking the distribution of the woodlice it depends on for food. It spends most of its time hidden away from light, emerging at night to hunt among leaf litter, garden debris, and damp structural crevices.

Despite its large jaws, the woodlouse spider is a reclusive, non-aggressive species that avoids confrontation and is rarely encountered in the open, spending the daylight hours concealed inside a silken retreat.

• Glossy, reddish-orange to orange-brown cephalothorax, legs, and chelicerae contrasting with a pale, dull grayish abdomen lacking obvious markings
• Unusually large, elongated fangs projecting forward, adapted specifically for piercing woodlice
• Six eyes clustered closely together rather than the eight found in many other spiders
• Medium-sized, moderately robust body with relatively long legs
• Distinguished from other spiders by its two-toned coloring and specialized, oversized chelicerae

Woodlouse spiders live in damp, dark microhabitats such as leaf litter, under logs and stones, within compost and mulch piles, and in damp corners of basements, garages, and sheds. Native to the Mediterranean region, the species has spread widely across Europe and North America, largely tracking the availability of its woodlice prey. It is most active at night and can be found year-round in mild climates, with peak activity in warmer months.

This spider is a nocturnal, ground-level hunter that does not build a capture web, instead actively searching out and seizing woodlice and other small invertebrates using its powerful, elongated jaws to penetrate their hard exoskeletons. During the day it hides inside a silk-lined retreat under bark, stones, or debris, emerging after dark to forage. Woodlouse spiders are solitary and generally avoid open, exposed areas, making them far less commonly seen than many other garden spiders despite being widespread.

Females lay eggs within a silk-lined retreat, often under a stone or log, and may remain nearby to guard the developing eggs and young spiderlings. Juveniles resemble smaller versions of the adults and grow through a series of molts over many months as they hunt increasingly larger woodlice. Development can take a year or more to reach maturity, with individuals overwintering in sheltered retreats in cooler climates.