Woodlouse Spider

Actual Size: 1/4-1/2″

Characteristics: Dark-red body and legs, with a shiny mahogany abdomen.


  • Nocturnal hunting spider
  • Helpful outdoors because they kill wood lice.
  • Can bite humans, but their venom poses no danger.

Pest Description

Woodlouse Spider Identification

The woodlouse spider, Dysdera crocata, is a nocturnal hunting spider commonly found in homes and gardens from New England to Georgia, the Midwest (Illinois and Indiana) and the Pacific Northwest. It is also commonly encountered in England, northern Europe and Australia. Dysdera crocata gets its name from its prey, woodlice, also known as isopods, pill bugs, roly-poly bugs and sow bugs.

The woodlouse spider is a medium-sized spider ranging from 1/4” to 1/2” in length. The front half of the spider and its legs are reddish orange to deep mahogany in color. The abdomen is grayish-white and looks like a bean. The prominent features of this spider are their large jaw and fangs, used to penetrate heavily armored pill bugs and roly-poly bugs.

Woodlouse spiders hunt at night without the use of a web. This spider hides during the day in a silken retreat constructed under rocks, logs, wood or other debris where isopods live. In homes, this spider is generally found in basements and areas with high humidity.

Woodlouse Spider Life Stages

Woodlouse spiders in Chicago are reported to mate in spring, with eggs being deposited shortly after. The courtship of these spiders is typically aggressive and mates risk injury from each other’s large fangs. Silk is not used for prey capture, but is used to construct retreats when molting and for egg laying. The eggs are suspended on silken threads of the retreat and about 70 eggs may be deposited at one time.

Unlike most spiders, the female woodlouse spider is believed to take care of her offspring. Newly hatched spiderlings initially stay with the mother, living in her retreat for a period of time before moving out on their own. Spiders reach maturity at around 18 months of age and may live up to three years.

Woodlouse Spider Threats

In August of 2018, a Facebook post with a photo of the woodlouse spider went viral regarding the lethal bite of a new spider in the U.S., however, these claims are false. The truth is that if handled, the woodlouse spider may be capable of inflicting a bite, but they do not possess venom that poses any danger to humans. The main symptom when bitten is minor pain and itching, typically lasting less than one hour, most likely due to the mechanical puncture of the skin.

The woodlouse spider is most commonly found around damp areas close to their food source, woodlice. They prefer rotting vegetation and wood and are most often found in basements, under stones and boards, around doors and windows and other areas that contain rotting wood. Gardeners tend to welcome these arachnids in their yards, as they help them get rid of woodlice, which are notorious plant pests.

Woodlouse Spider Extermination and Control

Woodlouse spiders are beneficial and when found outdoors they are best left alone to serve as predators of woodlice and pillbugs. To eliminate the possibility of these spiders coming indoors, follow these tips:

  • Patch up cracks and holes around the exterior of your home to prevent spiders and other insects from finding their way inside.
  • Nearly all spiders are predatory and require insects to survive. By eradicating their food source, spiders cannot survive.
  • Eliminate damp areas around the home where woodlice live such as piles of wood, debris, leaf litter and mulch.
  • If found indoors, a single spider can be controlled with a vacuum cleaner or captured and released alive back outside, wearing gloves to protect against being bitten.