Grass Spider, American Grass Spider
Agelenopsis sp.
Family Agelenidae (Funnel Weavers), Order Araneae
Physical Description
Elongated, teardrop-shaped body with a distinct cephalothorax and a long, tapering abdomen. They possess prominent, long spinnerets extending from the rear of the abdomen, which is a diagnostic trait for this genus.
Size Estimate
Body length typically 10-20mm (0.4-0.8 inches). Including legs, the span is roughly 25-50mm. This appears to be a mature or near-mature individual.
Coloration & Markings
Display two prominent dark longitudinal stripes running the length of the cephalothorax, bordering a lighter central band. The abdomen has a similar patterned band with a darker chevron or mottled markings.
Web Type
Characteristic flat, sheet-like funnel web with a retreat tube at one corner. Often built in low vegetation, grass, or corners of structures.
Eye Arrangement
Eight eyes arranged in two rows, with the top (posterior) row strongly curved forward, giving the appearance of three rows (2, 4, 2).
Leg Characteristics
Long, slender, and hairy legs with noticeable spines (macrosetae). Usually light brown or tan with faint darker banding or spots.
Venom & Safety Information
Venom Information
Contains agelenotoxins, primarily neurotoxic to insects. The venom is not considered medically significant to humans.
Medical Significance
Low danger level. Bites are rare because they are flight-oriented; symptoms are typically restricted to mild localized pain, itching, or redness similar to a bee sting.
Safety Recommendations
No action is usually needed. If found indoors, they can be safely captured using a cup and card method and released outside near foliage.
Habitat & Behavior
Habitat & Range
Common throughout North America in gardens, lawns, shrubs, and around building foundations. They prefer locations where they can anchor their flat sheet webs to foliage or architecture.
Behavior & Temperament
Extremely fast runners. They are shy, non-aggressive ambush hunters that hide in their funnel retreat until they feel vibrations from prey on the sheet web, then dart out at high speed.
Diet & Prey
Generalist insectivores; they eat a wide variety of small insects including crickets, flies, moths, and grasshoppers that land on their web.
Seasonal Activity
Peak activity occurs in late summer and early autumn when webs become largest and mature males wander in search of mates.
Description
The Grass Spider is a ubiquitous sight in North American yards. Distinguished by their incredible speed and the architectural sheet webs they weave across bushes and grass, they are essential garden guardians.
Key Features
Prominent long spinnerets at the end of the abdomen and two dark parallel stripes on the cephalothorax.
Similar Species
Wolf Spiders (Lycosidae) - lack the long spinnerets and build no funnel webs. Nursery Web Spiders (Pisauridae) - different eye arrangement and leg tapering.
Life Cycle
Females typically lay egg sacs in late summer or autumn in sheltered crevices. Adults usually die off after the first hard frost, and the spiderlings emerge in the spring.
Ecological Importance
Critical for natural pest control in residential and agricultural areas, keeping populations of flies and lawn-damaging insects in check.
Conservation Status
Not evaluated by IUCN; widely considered abundant and secure throughout their range.
Interesting Facts
Grass spiders are among the fastest spiders relative to their size; they can move at speeds that appear as a blur to the human eye when darting for prey.
Photography Tips
Focus on the long spinnerets at the rear and the stripes on the head. Using a fast shutter speed is recommended as they are prone to sudden movements.
Identified: 2026-07-15T21:54:49.490805