Turf running spider

Conservation Status

IUCN Red List

not listed

NatureServe

NNR - Unranked

Minnesota

not listed

Description

Turf running spider is a small crab spider. It occurs in North America and Europe. It is the most common spider in European orchards. In the United States it is occurs from Maine to Washington south to Illinois and New Mexico. It is found in deciduous and coniferous woodlands on the bark and leaves of trees, on shrubs, in grasses, and on the ground in leaf litter. In the spring, it is also frequently found on house siding and under eaves, where it likely benefits from the thermal regulation provided by sun-warmed surfaces.

The adult female is 3⁄16″ to ¼″ (4.5 to 6.1 mm) in length and has a ⅝″ to ¾″ (15 to 20 mm) legspan. The male is a little smaller, ⅛″ to 3⁄16″ (4.0 to 4.75 mm) in length. The body is soft, flattened, and smooth, with no rounded bumps (tubercles). It is weakly spined and is covered with soft, leaning (recumbent) hairs. The color can vary from mostly brown with pale mottling and dark brown markings, to mostly pale with brown markings.

The covering (carapace) of the front part of the body (cephalothorax) is as wide as long and is smoothly rounded on the sides, somewhat flattened when viewed from the side and somewhat circular when viewed from above. It is reddish brown on the sides with a broad pale band in the middle. There is a short, narrow, dark, longitudinal stripe on the rear margin, and a narrow, irregular, pale stripe on the lateral margins. On the female, a light V-shaped mark, lighter than the pale band, begins at about the middle of the carapace and extends forward to the anterior median eyes (AME). There are eight eyes arranged in two rows of four. None of the eyes are on tubercles and all of them are small. The four eyes in the back row are all the same size. The posterior median eyes (PME) are closer to the posterior lateral eyes (PLE) than they are to each other. The median ocular area (MOA), the area defined by the middle four eyes, is wider than long.

The abdomen is flat, longer than wide, widest just beyond the middle, and broadly pointed at the tip. It is usually pale above and dark on the sides. There is a dark brown, elongated, oval-shaped mark (cardiac mark) on the front half, and dark chevrons on the rear half. The chevrons are sometimes interrupted, either once in the middle or once on each half. The underside of the abdomen is pale. Males are often darker, sometimes unifromly dark brown.

The legs are long and slender. They are longer and thinner on the male than on the female. They first, third, and fourth pairs of legs are nearly the same length and thickness, the second pair is only slightly longer. The front two pairs project outward rather than forward (laterigrade), allowing the spider to move quickly sideways, like a crab. This is the feature that gives the superfamily its common name. The legs are yellowish and slightly darker at the end of each segment. They are often speckled with brown on the side that faces forward (prolateral surface). The third segment (femur) on the front legs has three erect black spines on the upper surface. On each leg the last leg segment (tarsus) has a two claws, a well-developed, dense, brush-like tuft of microscopic hairs below (scopula), and a dense, brush-like tuft of microscopic hairs at the end (claw tuft). The claws, scopulae, and claw tufts are not visible to the naked eye.

Size

Female Body Length: 3⁄16″ to ¼″ (4.5 to 6.1 mm)

Male Body Length: ⅛″ to 3⁄16″ (4.0 to 4.75 mm)

Legspan: ⅝″ to ¾″ (15 to 20 mm)

Web

Running crab spiders do not build snares, retreats, or nests.

Similar Species

Eastern running crab spider (Philodromus vulgaris) is nearly identical in size and shape but is often more pale and “washed-out” in appearance. While P. cespitum is unique among its immediate relatives for being predominantly brown, P. vulgaris and other members of the genus tend toward grayer, more neutral tones.

Habitat

Woodlands

Ecology

Foraging

Active hunter (Cursorial Hunter)

Prey

Behavior

The adult is able to move very fast, and its movements are rapid and erratic. While it may wait in ambush, it often hunts by running after prey. This is the feature that gives the family its common name.

Life Cycle

Season

Distribution

Sources

24, 30, 82, 83.

Biodiversity occurrence data published by: Minnesota Biodiversity Atlas (accessed through the Minnesota Biodiversity Atlas Portal, bellatlas.umn.edu. Accessed 5/4/2026).

Philodromus cespitum (Walckenaer, 1802) in GBIF Secretariat (2023). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org. Accessed 5/4/2026.

Dondale, C. D. (1961). Revision of the aureolus group of the genus Philodromus (Araneae: Thomisidae) in North America. The Canadian Entomologist 93: 199-222.