Hobo Spiders

What Are Hobo Spiders?

Hobo spiders, scientifically known as Tegenaria agrestis, are a species of funnel weaver spiders native to Europe. They are often referred to as "aggressive house spiders" or "funnel web spiders" in the United States, where they have become an introduced species. Here is a comprehensive overview of hobo spiders:

Are Hobo Spiders Harmful?

Hobo spiders (Eratigena agrestis) are often considered potentially harmful due to concerns surrounding their bites and the possibility of them becoming household pests. However, the degree of harm they pose is a subject of ongoing debate among arachnologists and public health officials. Here are some of the ways in which hobo spiders might be considered harmful:

• Venom and Bite Concerns: Historically, hobo spiders were classified as medically significant due to claims that their bites could cause necrotic lesions similar to those from brown recluse spiders. These concerns were largely based on anecdotal evidence and limited studies conducted in the 1980s and 1990s. Reported symptoms of a hobo spider bite included redness and blistering at the bite site, headache, fatigue, nausea, and development of open sores with slow healing (in extreme cases). However, more recent research — including evaluations by the Centers for Disease Control and Prevention (CDC) and other toxicology experts — has challenged this reputation. Multiple controlled studies have failed to demonstrate consistent necrotic effects from hobo spider venom, and there is no definitive scientific evidence that their bites are medically dangerous to humans. That said, like many spider bites, individual reactions can vary. Some people may experience localized pain, itching, or mild swelling, which, while not life-threatening, could be uncomfortable and cause concern, particularly if misidentified or left untreated.
• Allergic Reactions: Though rare, any spider bite can potentially trigger an allergic reaction, especially in sensitive individuals. These reactions might include rash or hives, swelling beyond the bite area, and respiratory distress in extreme cases (anaphylaxis). While not specific to hobo spiders, this potential makes any spider interaction a cause for vigilance.
• Infestation and Nuisance Factor: Hobo spiders are aggressive hunters and do not spin webs to catch prey; instead, they build funnel-shaped retreats and actively search for insects. Indoors, they may become a nuisance for homeowners, especially in basements, crawl spaces, or lower levels where they seek shelter. Infestations can result in psychological stress (arachnophobia), disruption of indoor spaces, and increased risk of bites if spiders feel trapped or provoked.

Learn more: Are Hobo Spiders Poisonous?

Hobo Spider Appearance

Hobo spiders (Tegenaria agrestis) have distinct physical characteristics that can help in their identification. Here is a detailed description of what they look like:

• Size: Hobo spiders are medium-sized spiders, with males typically measuring between 8 to 15 mm in body length, and females ranging from 9 to 18 mm. The females are generally larger than the males.
• Color: They have a light to medium brown or tan cephalothorax (the front part of the body), which is often marked with a distinctive chevron-shaped pattern. This chevron pattern can vary in intensity but is a key identifying feature. The abdomen is usually slightly darker than the cephalothorax.
• Legs: Hobo spiders have long, slender legs that are typically a similar color to the cephalothorax and abdomen. Their legs are often covered in fine hair, giving them a slightly fuzzy appearance.
• Eyes: Like most spiders, hobo spiders have eight eyes arranged in two rows. These eyes are relatively small and not as prominent as those of some other spider species.
• Abdomen: The abdomen of hobo spiders is generally oval-shaped and lacks any distinct markings or patterns, except for being slightly darker than the cephalothorax.
• Spinnerets: At the rear end of the abdomen, hobo spiders have spinnerets, which they use to produce silk for constructing their webs.
• Web: While not a physical characteristic of the spider itself, hobo spiders are known for their funnel-shaped webs. These webs have a tubular retreat at the back where the spider hides. The funnel web serves as both a shelter and a trap for prey.

Hobo spiders can be confused with other spider species, particularly the giant house spider (Eratigena atrica), which is native to Europe as well and has a similar appearance. Proper identification often requires close examination of physical characteristics, such as the chevron pattern on the cephalothorax and the shape of the web they construct. If you are uncertain about the identification of a spider in your area, it may be advisable to consult with a local expert or entomologist for confirmation.

Hobo Spider Habitats

Hobo spiders (Tegenaria agrestis) are typically found in specific habitats, and their distribution is more prominent in certain regions. Here's where you might find hobo spiders:

• Geographic Range: Hobo spiders are native to Europe, but they were introduced to the Pacific Northwest of the United States in the early 20th century. As a result, their distribution is more concentrated in the Pacific Northwest region, including parts of Washington, Oregon, Idaho, and Montana.
• Indoor Habitats: Within their introduced range, hobo spiders are often encountered in indoor environments. They prefer dark, secluded places, such as basements, crawlspaces, garages, and storage areas. These spiders construct funnel-shaped webs in these locations, with a retreat at the back of the web.
• Outdoor Habitats: While hobo spiders are primarily associated with indoor environments, they can also be found outdoors, especially in areas with suitable hiding spots. They may inhabit woodpiles, under rocks, and in dense vegetation. However, they are less commonly encountered in outdoor settings compared to indoor spaces.
• Web Locations: Hobo spiders build their funnel-shaped webs close to their hiding places. These webs are often positioned in corners, crevices, and along walls, providing them with a strategic location to capture prey.
• Human Structures: Hobo spiders are often referred to as "house spiders" because they have adapted to living in close proximity to human dwellings. They are frequently found in homes, particularly in areas with a cooler and moister climate.
• Preferred Climate: Hobo spiders thrive in areas with a temperate climate, where temperatures are not extreme. They are more active during the cooler months of the year and may become less active or seek shelter during hot, dry periods.
• Identification Challenges: Identifying hobo spiders can be challenging due to their similarity to other spider species, such as the giant house spider (Eratigena atrica), which shares their introduced range. Therefore, if you suspect the presence of hobo spiders, it's advisable to seek expert identification to confirm their presence.

Hobo spiders are primarily found in the Pacific Northwest of the United States and are commonly associated with indoor environments, particularly in dark and sheltered areas like basements and crawlspaces. While they can also be encountered outdoors, their distribution is more concentrated in human-made structures within their introduced range.