Data Sheets: Hobo Spider (Eratigena agrestis)

Hobo Spider (Eratigena agrestis)

Scientific Classification:

• Kingdom: Animalia
• Phylum: Arthropoda
• Class: Arachnida
• Order: Araneae
• Family: Agelenidae
• Genus: Eratigena
• Species: E. agrestis

Introduction

The Hobo Spider, scientifically known as Eratigena agrestis, is a member of the Agelenidae family, commonly known as funnel-web spiders due to the shape of their webs. Originally from Europe, this species has become well-established in the Pacific Northwestern United States, including Oregon. The spider has garnered attention due to its reputation, once believed to be a significant medical threat, although recent studies suggest that its venom is less harmful to humans than previously thought.

Description

The Hobo Spider is a medium-sized spider, with adult males ranging from 7 to 14 mm in body length and females from 9.5 to 16.5 mm. They exhibit a brownish color with a distinct pattern of darker stripes on their cephalothorax, which may appear mottled. The abdomen has several chevron-shaped markings, which can be quite subtle and vary between individuals. The legs are long and unmarked, enhancing their ability to move quickly.

Habitat

Hobo Spiders prefer to dwell in dark and moist environments. In their natural habitat, they are commonly found under rocks, logs, and in dense vegetation. However, their adaptation to urban environments is notable. They often reside in basements, crawl spaces, and other undisturbed parts of buildings.

Web and Feeding Habits

The Hobo Spider constructs a funnel-shaped web which serves both as a retreat and a trap for prey. The web opens to a wide, flat surface that tapers into a funnel where the spider hides. These webs are often built at ground level and can be found along walls and between objects on the ground. The Hobo Spider is a nocturnal hunter, feeding primarily on insects that blunder into its sticky web.

Venom

The venom of the Hobo Spider was once feared for its alleged necrotic properties, similar to those of some recluse spiders. However, subsequent research has largely debunked this view, showing that while the bite can cause pain and swelling, it does not result in the severe necrotic lesions once attributed to it. Medical intervention is rarely necessary, and symptoms typically resolve with minimal treatment.

Reproduction

Mating typically occurs in the early fall. Males roam in search of females and upon finding one, will mate with her multiple times. Females lay egg sacs which are hidden within the web or in other secluded locations. Each sac can contain up to several hundred eggs. The female guards the eggs until they hatch, and the spiderlings disperse soon after emerging.

Habitat in Oregon

In Oregon, the Hobo Spider is found in both rural and urban environments. It thrives particularly well in human-altered landscapes such as homes and gardens where it can find numerous hiding spots and ample insect prey. These spiders are particularly prevalent in the basement areas of homes, where their funnel webs can be constructed in corners and along the edges of walls. Their presence across various habitats in Oregon highlights their adaptability and effectiveness in colonizing new environments.

Conclusion

The Hobo Spider, a notable resident of Oregon's spider fauna, plays a functional role in controlling insect populations. Understanding the true nature of its bite and ecological role can help mitigate undue concern and promote informed coexistence with this widespread arachnid.