Agelenopsis

Giebel, 1869

American grass spiders, grass spiders, funnel weavers

Species Guides

11

Agelenopsis is a of funnel-web spiders native to North America, commonly known as American grass spiders. They construct distinctive sheet webs with a funnel-shaped retreat at one edge, using non-sticky silk that relies on the spider's rapid speed to capture prey. The genus includes fourteen recognized as of 2025, with body lengths ranging up to approximately 19 mm. They are characterized by eight arranged in three rows (two, four, two) and two prominent held parallel to each other.

Agelenopsis aperta by no rights reserved, uploaded by Jesse Rorabaugh. Used under a CC0 license.Common Spiders U.S. 221 by James Henry Emerton (1847 – 1931). Used under a Public domain license.Common Spiders U.S. 227 by James Henry Emerton (1847 – 1931). Used under a Public domain license.

Pronunciation

How to pronounce Agelenopsis: //ˌæɡɪlɪˈnɒpsɪs//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Agelenopsis can be distinguished from the related European Agelena by two quasiparallel dark lines running from the to the beginning of the on the , whereas Agelena has curved, irregular lines that often meet at the end. Females can be further distinguished by the length of the front leg row. From the western genus Hololena, Agelenopsis differs by having long usually held parallel to each other, versus Hololena's short spinnerets directed somewhat inward. The eye arrangement—two eyes in the top row, four in the middle, and two in the bottom row spaced wider than the top pair—is diagnostic for the genus.

Images

Habitat

Found in diverse including grasslands, meadows, lawns, gardens, and shrubbery. In desert regions, occupies desert grassland and scrub habitats. Often abundant in urban and suburban environments, where they construct webs on vegetation, hedges, and low plants. In eastern Ukraine, occupy urbanized environments including cities, towns, and nature reserves.

Distribution

Native to North America, ranging from southern Canada through the United States to northern Central America. Individual have more restricted ranges: A. pennsylvanica occurs in the northeastern and mid-Atlantic United States; A. aperta inhabits desert regions of the southwestern United States and northern Mexico; A. potteri has been introduced to Europe, with established in Ukraine (detected in 19 of 25 administrative regions as of 2025), Italy, and the United Kingdom.

Seasonality

are primarily active from late spring through autumn. In temperate regions, peak activity occurs during summer months. In Ukraine, show adult activity from June to October, with peak numbers in August and September; last observations of single females extend into November.

Diet

Feeds on small insects that blunder onto the web sheet, including flies, small , and other arthropods. Relies on speed rather than sticky silk to capture prey, dashing out from the funnel to subdue victims and drag them back to the retreat.

Life Cycle

Development includes , spiderling, and stages. Spiderlings construct webs and may disperse by ballooning on silk threads. Sexual maturity is reached within one season in most of the range; some southern may have two annually. In desert-adapted , timing correlates with seasonal prey availability and temperature conditions.

Behavior

Constructs horizontal sheet webs 8-12 inches across with a funnel-shaped retreat at one edge. The web lacks adhesive properties; prey capture depends on the spider's extreme sensitivity to vibrations and rapid running speed. When threatened, the spider retreats into the funnel with remarkable speed. Males wander in search of females and may enter homes. Courtship involves male vibratory displays on the female's web, including lateral swaying and web flexing; successful males induce cataleptic paralysis in females before mating. Sexual has been documented, with hungry and aggressive females consuming mates; cannibalistic females produce heavier with increased hatching success.

Ecological Role

of small insects in grassland, garden, and shrubland . Contributes to structure in desert grasslands and lava bed . Serves as prey for birds, larger spiders, and other arthropod predators. In invaded European habitats, integrates into local spider communities without documented major ecological disruption.

Human Relevance

Generally harmless to humans; bites are extremely rare and medically insignificant. Often noticed in gardens and yards during foggy mornings when dew condenses on webs. Occasionally enters homes when males wander seeking mates. One , A. potteri, has become established in Europe through human-mediated transport. The serves as a model organism for behavioral research, particularly regarding selection, courtship , and .

Similar Taxa

  • HololenaAlso Agelenidae with similar sheet-and-funnel webs, but has short directed inward rather than long parallel spinnerets; restricted to western North America.
  • AgelenaEuropean funnel-web spiders with curved, irregular cephalothoracic lines that often meet at the end, versus Agelenopsis's quasiparallel lines.
  • Eratigena (hobo spider)Formerly Tegenaria; larger Agelenidae with different arrangement and more robust body; medically significant bite reputation (though often overstated).

Sources and further reading