Oblong Running Spider, Slender Crab Spider
Tibellus oblongus
Philodromidae (Running Crab Spiders), Order Araneae. Characterized by speed and flattened bodies.
Physical Description
Elongated, slender, cigar-shaped body with a streamlined cephalothorax. The abdomen is notably long and tapers at the end. Their body is relatively flat, allowing them to press tight against blades of grass.
Size Estimate
Body length typically 7-10mm for females, males slightly smaller. Leg span approximately 20-30mm. This specimen appears to be an adult.
Coloration & Markings
Pale tan to straw-colored base. Featuring three distinct longitudinal dark stripes running the length of the body: one central stripe and two lateral stripes. Some specimens have small black dots near the rear of the abdomen.
Web Type
None. This is an active hunting spider that does not build webs for prey capture, though it uses silk for egg sacs and draglines.
Eye Arrangement
Eight eyes in two rows. The eyes are small and relatively equal in size compared to jumping spiders, arranged on a slightly raised area of the cephalothorax.
Leg Characteristics
Long, slender legs. In a resting position, the first and second pairs of legs are often extended forward while the fourth pair is extended backward, creating a linear silhouette.
Venom & Safety Information
Venom Information
Neurotoxic venom optimized for paralyzing small insects. Low potency and not considered dangerous to humans.
Medical Significance
Harmless. Bites are extremely rare due to their timid nature. If a bite occurs, it usually results in localized, minor redness and itching similar to a mosquito bite.
Safety Recommendations
No special safety measures required. If found indoors, they can be easily moved outside using a cup and a piece of paper. They pose no threat to pets or humans.
Habitat & Behavior
Habitat & Range
Holarctic distribution across North America, Europe, and Northern Asia. Commonly found in tall grasses, meadows, and dunes where they camouflage perfectly.
Behavior & Temperament
Diurnal active hunter. It relies on speed and camouflage rather than silk traps. It is extremely fast and will flatten itself against vegetation to remain undetected. Very shy and non-aggressive.
Diet & Prey
Small insects including flies, leafhoppers, and small moths found in grasslands. They ambush prey with a sudden burst of speed.
Seasonal Activity
Most active from late spring through late summer. They often overwinter as sub-adults in leaf litter or under bark.
Description
An elegant, highly specialized spider that has evolved to mimic the appearance of dried grass. Its long, slender body and lateral stripes make it nearly invisible when it stretches out along a stalk. A fascinating example of cryptic camouflage.
Key Features
Elongated cigar-shaped body, three dark longitudinal stripes, and the habit of resting with legs stretched out linearly.
Similar Species
Other Tibellus species (distinguished by microscopic genital examination) and some Tetragnatha (Long-jawed Orb-weavers), which build large horizontal orb webs.
Life Cycle
Females produce a flat, white silken egg sac often attached to a leaf or blade of grass. They may guard the sac until spiderlings emerge. Lifespan is typically one year.
Ecological Importance
Significant predator in grassland ecosystems, helping to regulate populations of agricultural pests like leafhoppers.
Conservation Status
Not evaluated by IUCN, but generally widespread and common within suitable tall-grass habitats.
Interesting Facts
Unlike 'true' crab spiders (Thomisidae), running crab spiders like Tibellus have legs of roughly equal length, allowing them to run forward very quickly rather than just sideways.
Photography Tips
Photograph from a top-down angle to highlight the stripes and body shape. Avoid casting a shadow, as they are sensitive to light changes and will run quickly if startled.
Identified: 2026-07-16T18:58:17.390925