Agelenopsis pennsylvanica

Distinguished from other Agelenopsis species by male genitalia: embolus makes complete circle with tip perpendicular to cymbium. Long spinnerets held parallel to each other separate Agelenopsis from Hololena (short, inward-directed spinnerets). Distinguished from A. potteri (closest relative) by specific genitalic structures. Eye arrangement typical of genus: anterior median eyes largest, posterior median smallest; anterior eyes less than radius apart, posterior eyes equidistant.

Medium-sized spider with females 9–14 mm in body length, males 7–12 mm. Carapace displays dark markings that are often faded. Sternum is yellow-orange with a large dark V-shaped mark, or entirely black in darker individuals. Abdomen has similar patterning, with speckled sides and pale venter with broad dusky black median area. Hind spinnerets have apical segment about twice as long as basal segment. Females possess skull-shaped bursa opening with spermathecae nested vertically. Males are distinguished by coiling embolus that makes a full circle with pointed tip perpendicular to cymbium.

Open grassy habitats, floodplain forests, and areas near bodies of water. Correlated with high water availability and humidity. Found on ground, in understory vegetation, trees, old field lawns, and around houses. Web placement varies seasonally.

Widespread across United States. Documented in Colorado, Connecticut, Idaho, Illinois, Kansas, Louisiana, Massachusetts, Michigan, North Dakota, Ohio, Oregon, Pennsylvania, Tennessee, Utah, West Virginia, and at least 6 additional states. Most common from New England and Great Lakes states westward to Nebraska and eastern Colorado, south to Arkansas, Mississippi, and northern Georgia. Disjunct populations in Washington and Oregon.

Sexual maturity occurs late August to September. Egg sacs produced October to November. Females remain with egg sacs until death. Juvenile stages show boldness and aggressive foraging behaviors correlated with penultimate instar in wild individuals.

Carnivorous; feeds on insects captured in web including hemipterans (true bugs), homopterans, coleopterans (beetles), hymenopterans (bees, ants, wasps, sawflies), dipterans (true flies), and orthopterans (grasshoppers, locusts, crickets).

Annual or short-lived. Eggs laid in large conical egg sacs (18–236 eggs) enclosed in thin silk sac covered by debris layer. Females exhibit maternal care, remaining with egg sacs until death. Multiple females may aggregate under tree bark with touching or overlapping egg masses. Sexual maturity in late summer/early fall; overwintering stage not explicitly documented but likely eggs or early instars.

Ambush predator that waits at funnel entrance, using high-velocity movements to subdue prey contacting web. Exhibits sexual cannibalism: females commonly cannibalize males during mating. Pre-copulatory cannibalism occurs in ~36% of virgin females; females that consume first male before copulation show increased reproductive success with heavier egg sacs and higher hatching success. Boldness and foraging aggression in juveniles are phenotypically plastic responses to environmental conditions, not observed in laboratory-reared individuals. Males approach females cautiously, creating vibrational signals; receptive females enter cataleptic paralysis. Males depart web before female awakens to avoid cannibalism.

Predator controlling insect populations in grassy habitats. Serves as prey for other spiders including Parasteatoda tepidariorum (common house spider) and Phidippus audax (bold jumper). Cuticular microbiota interactions with environmental bacteria influence behavior and potentially fitness.

Bites cause localized symptoms including itching, swelling, redness, and occasionally back pain; symptoms persist 1–10 days. Used extensively in research on sexual cannibalism, pre-copulatory cannibalism, boldness, aggressive foraging behavior, and microbial influences on reproduction and mating. Occasional indoor visitor, particularly juveniles and mature males.

• Agelenopsis potteriClosest relative; distinguished by genitalic morphology and geographic distribution
• Hololena spp.Also Agelenidae with funnel webs; Hololena has short, inward-directed spinnerets vs. long parallel spinnerets in Agelenopsis; Hololena restricted to western third of U.S.
• Agelenopsis naeviaSimilar egg sac morphology; distinguished by genitalic features and coloration patterns
• Agelenopsis oklahomaSimilar size, coloration, morphology, and copulatory behavior; potentially capable of interspecific mating but mutual indifference or aggression observed in encounters

• spider
• funnel-web
• agelenidae
• sexual cannibalism
• ambush predator
• research model
• grassland
• united states

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