American Grass Spider
Agelenopsis species
Agelenidae (Funnel Weavers), Order Araneae
Physical Description
Elongated, teardrop-shaped abdomen tapering to long, prominent spinnerets. The cephalothorax is relatively large with a distinct 'waist' (pedicel). The body texture appears slightly fuzzy or hairy due to fine sensory setae.
Size Estimate
Body length 10-20mm; total leg span approximately 30-50mm. This appears to be a sub-adult or adult specimen.
Coloration & Markings
Grayish-tan to brown base color. Two prominent dark longitudinal stripes run the length of the cephalothorax, and the abdomen typically features a light central band bordered by darker mottled patterns.
Web Type
Builds large, flat sheet webs with a characteristic funnel-shaped retreat at one end. Webs are commonly found on low vegetation, grass, or building foundations.
Eye Arrangement
Eight eyes arranged in two rows. The eyes are fairly small and uniform in size, oriented to detect movement across the surface of the web.
Leg Characteristics
Long, slender, and tapering legs covered in fine bristles and spines. Legs are typically tan with darker banding or mottling, designed for high-speed running on sheet silk.
Venom & Safety Information
Venom Information
Possess venom designed to paralyze small insects. The venom is not considered medically significant to humans; it is weakly neurotoxic but lacks the chemicals necessary to cause severe reactions in mammals.
Medical Significance
Harmless. Bites are extremely rare because the spider is timid. If a bite occurs, it usually results in mild localized swelling, itching, or redness similar to a bee sting.
Safety Recommendations
No special precautions needed. To relocate from a house, use a cup and a piece of paper. They are more likely to run away than to bite.
Habitat & Behavior
Habitat & Range
Common throughout North America. Found in lawns, gardens, low shrubs, and occasionally indoors near windows or doorways where light attracts prey.
Behavior & Temperament
Extremely fast runners. They act as ambush hunters, waiting at the mouth of their funnel and darting out to grab prey that lands on the sheet. Generally shy and will retreat rapidly if disturbed.
Diet & Prey
Insects such as flies, crickets, and moths. They do not use sticky silk; they rely on speed to overtake prey before it can escape the sheet web.
Seasonal Activity
Most visible in late summer and early autumn when they reach adult size and their large webs become prominent in the morning dew.
Description
The American Grass Spider is a common and beneficial predator often seen making 'dew-covered' sheet webs in lawns. It is easily identified by its lightning-fast speed and the two long, finger-like spinnerets at the end of its abdomen.
Key Features
Prominent long spinnerets, two dark stripes on the cephalothorax, and funnel-shaped web retreat.
Similar Species
Wolf Spiders (Lycosidae) are often confused but lack the long spinnerets and do not build funnel webs. Barn Funnel Weavers (Tegenaria) look similar but are mostly found indoors and have different markings.
Life Cycle
Females produce a disc-shaped egg sac in autumn and usually die shortly after. Spiderlings hatch in spring and disperse via ballooning. Lifespan is approximately one year.
Ecological Importance
Highly beneficial for natural pest control. They consume large quantities of lawn pests, such as gnats and leafhoppers, and serve as food for birds and wasps.
Conservation Status
Not evaluated by IUCN; considered stable and very common throughout its range.
Interesting Facts
The silk of their web is not sticky; the spider relies entirely on its high-speed vibration detection and physical speed (up to 2 feet per second) to catch prey.
Photography Tips
Focus on the long spinnerets at the rear. Morning photography is best when dew reflects off the web, providing context for the spider's behavior.
Identified: 2026-06-22T03:55:49.249277