American Grass Spider, Grass Spider, Funnel Weaver
Agelenopsis pennsylvanica
Agelenidae (Funnel-Weavers), Order Araneae
Physical Description
Elongated body with a distinct tapering abdomen, featuring prominent, elongated spinnerets at the rear tip which are characteristic of funnel weavers. The cephalothorax is oval and slightly flattened, marked by distinct longitudinal dark bands. The body has a light covering of fine setae.
Size Estimate
Body length approximately 10 to 18 millimeters, with a total leg span reaching up to 40 to 50 millimeters. This specimen appears to be a healthy adult or sub-adult.
Coloration & Markings
Predominantly brown and tan with contrasting patterns. The cephalothorax features two broad, dark brown longitudinal stripes flanking a lighter median band. The abdomen has a mottled pattern of brown, gray, and tan, often with a lighter yellowish-brown median stripe bordered by darker areas.
Web Type
Builds a horizontal, sheet-like web that ends in a funnel-shaped retreat at one edge, typically constructed low to the ground in grass, bushes, or around structural foundations.
Eye Arrangement
Eight eyes arranged in two distinct, slightly curved rows of four. The eyes are fairly uniform in size, characteristic of the Agelenidae family, providing good forward and lateral vision.
Leg Characteristics
Long, robust legs featuring prominent spines (spines clearly visible on the tibiae and metatarsi) and distinct dark banding. The legs are held radiating outward in a flat, spread posture ready for rapid movement.
Venom & Safety Information
Venom Information
Contains mild venom used primarily to subdue insect prey. It is not considered dangerous to humans.
Medical Significance
Harmless to humans. Bites are rare, usually only occurring if the spider is trapped directly against the skin. Symptoms are typically minor, comparable to a mild ant sting or mosquito bite, resolving quickly without medical intervention.
Safety Recommendations
No special precautions needed beyond standard caution. If found indoors, they can be safely relocated outside using a cup and piece of paper. First aid for rare bites involves simply washing the area with soap and water.
Habitat & Behavior
Habitat & Range
Widely distributed across North America. Prefers grassy fields, lawns, gardens, low shrubs, and often wanders near or inside human dwellings, particularly around foundations, basements, and sinks where moisture attracts them.
Behavior & Temperament
Very fast, agile runners. They are non-aggressive and typically flee rapidly toward their funnel retreat when disturbed. They are active hunters within the context of their web architecture.
Diet & Prey
Feeds primarily on flying and crawling insects, including flies, crickets, beetles, and moths, which become trapped on the non-sticky sheet web.
Seasonal Activity
Most active and visible during late summer and autumn when adults reach full size and males actively wander in search of mates. Overwinters primarily in the egg stage.
Description
The American Grass Spider is a familiar and beneficial inhabitant of North American lawns and gardens. Easily recognized by the prominent spinnerets at the rear of its abdomen and the distinctive dark stripes running down its cephalothorax, this swift hunter constructs intricate sheet webs ending in a cozy retreat funnel. Though they occasionally wander indoors during autumn, they are completely harmless to humans and play a vital role in controlling insect populations.
Key Features
Prominent, elongated posterior spinnerets; two dark longitudinal stripes on the cephalothorax; highly spiny legs; construction of a sheet web with a funnel retreat.
Similar Species
Wolf spiders (Lycosidae), which lack the prominent spinnerets and funnel webs, and nursery web spiders (Pisauridae), which generally do not build webs for trapping prey.
Life Cycle
Females construct tough, disc-shaped silk egg sacs in autumn, hiding them under rocks, bark, or crevices. Spiderlings emerge in spring, undergoing multiple molts to reach maturity by late summer or autumn.
Ecological Importance
Acts as an effective natural pest control agent by consuming large numbers of agricultural and household insect pests, while also serving as a food source for birds, small mammals, and reptiles.
Conservation Status
Not evaluated by the IUCN, but populations are secure, widespread, and common throughout their natural range.
Interesting Facts
Grass spiders possess some of the fastest acceleration rates among terrestrial animals when darting toward prey or escaping threats. Their web silk is non-sticky; instead, insects are disoriented by the dense, crisscrossing mesh of threads.
Photography Tips
Photograph from a top-down or slight side angle to clearly capture the diagnostic longitudinal stripes on the cephalothorax and the prominent spinnerets. Use natural, diffused lighting and a macro lens while maintaining a calm distance to avoid startling the spider into fleeing.
Identified: 2026-10-05T10:50:37.095719