Western Funnelweb Spider

Pronunciation

How to pronounce Agelenopsis aperta: /əˌd͡ʒɛlɪˈnɒpsɪs əˈpɜːrtə/

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Summary

Agelenopsis aperta, commonly known as the desert grass spider or funnel-web spider, is characterized by its funnel-shaped webs and distinct coloration. It thrives in arid environments of the southern United States and engages in elaborate mating rituals. While it possesses venom used for subduing prey, its bites to humans are rarely harmful.

Physical Characteristics

The body length of Agelenopsis aperta is about 13–18 mm, with a gray, brown, and black coloration. The cephalothorax is tan or gray with two longitudinal brown stripes, while the abdomen is tan with two black stripes. The species has relatively long legs adapted for running, prominent spinnerets, and eight eyes arranged in two rows in an arc.

Identification Tips

Look for the characteristic funnel-shaped webs made of non-sticky silk, typically close to the ground. The light body color with two stripes is common among funnel weaving spiders.

Habitat

Desert grass spiders prefer dry and arid climates, and can be found in grasslands, lava beds, and rangelands. They may also inhabit buildings in these regions, constructing webs in undisturbed corners.

Distribution

Found across the southern United States from southern California to Texas and as far south as northwestern Mexico.

Diet

Agelenopsis aperta preys on insects, particularly grasshoppers and aphids, as well as other spiders. They actively hunt at night, using their webs to capture prey.

Life Cycle

Eggs are laid in a communal web, where spiderlings initially stay together before dispersing to build individual webs. Competitive behaviors are seen among siblings.

Reproduction

Mostly monogamous with some instances of polygyny. Males perform elaborate courtship rituals, swaying their bodies to induce a cataplectic state in females before mating.

Predators

Major predators include birds. There is higher predation pressure in woodland habitats compared to grassland habitats.

Ecosystem Role

As predators of insects, Agelenopsis aperta plays a significant role in controlling insect populations within their habitats.

Health Concerns

Bites from Agelenopsis aperta are typically harmless, but there have been rare cases in Southern California with mild symptoms. These bites have been confused with bites from similar species.

Collecting Methods

• Hand collection in natural habitats
• Vacuum sampling from webs

Preservation Methods

• Drying specimens
• Ethanol preservation

Similar Taxa

• Eratigena agrestis

Misconceptions

Despite being venomous, bites from A. aperta are not considered medically significant and have been misattributed to other species.

Tags

• Arachnids
• Spiders
• Agelenopsis
• Funnelweb spiders
• Desert grass spider