Roly Poly Killer

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Compiled by Whitney Cranshaw, Colorado State University:

Colorado Insects of Interest

Roly-poly Killer

Woodlouse Hunter
Figure 1. Dysdera crocata adult.
Scientific Name: Dysdera crocata Drury

Class: Arachnida (Arachnids)
Order: Araneae (Spiders)
Family: Dysderidae

Identification and Descriptive Features: Dysdera crocata (Figure 1 and 2) is a spider of moderate-size, ranging 9-15 mm in length. The front half of the in spider (cephalothorax) and the appendages are orange or reddish orange. The abdomen is grayish white. Perhaps the most striking feature is the very large jaws and associated fangs (Figure 2).

Distribution in Colorado: An introduced species, Dysdera crocata can now likely found in residential areas statewide.

Figure 2. Dysdera crocata adult with fangs opened.
Life History and Habits: Dysdera crocata is primarily a predator of the common terrestrial isopods known as “sowbugs” and “pillbugs” (“roly-polies”), and its large fangs help to penetrate these heavily armored prey. Other arthropods may also be taken as food.

The spider is a nocturnal hunter and during the day is usually found under rocks, wood or other covering debris where isopods similarly occur. In homes, Dysdera crocata is almost always found in basements and other sites where humidity is high.

Figure 3. Dysdera crocata with pillbug.
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 the newly hatched spiderlings stay with the mother and use the retreat for the first few weeks after egg hatch.

The spiders mature in about 18 months and, at least in captivity, may live an additional couple of years. Generations overlap and adults and immature forms can be found year round. Mating has been observed to occur in spring, and may happen at other times given the continuously overlapping generations of this species.

If handled their large fangs may be capable of inflicting a bite but they do not possess venom that poses any danger to humans. These are secretive spiders that are not aggressive and not harmful.

Related Species: Dysdera crocata is an introduced species of spider, native to Europe. It is the only representative of the family Dysderidae that occurs in Colorado.

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.