The hobo spider (''Eratigena agrestis'', formerly ''Tegenaria agrestis'') is a member of the family of

spider Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...

s known colloquially as funnel web spiders, but not to be confused with the Australian funnel-web spider. Individuals construct a

funnel A funnel is a tube or pipe that is wide at the top and narrow at the bottom, used for guiding liquid or powder into a small opening. Funnels are usually made of stainless steel, aluminium, glass, or plastic. The material used in its construct ...

-shaped structure of silk sheeting and lie in wait at the small end of the funnel for prey insects to blunder onto their webs. Hobo spiders sometimes build their webs in or around human habitations. The hobo spider lays its eggs in September and they hatch during late spring. After the male hobo spider mates it dies.

Taxonomy

The species was first described in 1802 by naturalist

Charles Athanase Walckenaer Baron Charles Athanase Walckenaer (25 December 1771 – 28 April 1852) was a French civil servant and scientist. Biography Walckenaer was born in Paris and studied at the universities of University of Oxford, Oxford and University of Glasgow ...

as ''Aranea agrestis'', in reference to its western European habitat in fields, woods, and under rocks. In 1841, Walckenaer transferred the species to the genus ''

Tegenaria ''Tegenaria'' is a genus of fast-running funnel weavers that occupy much of the Northern Hemisphere except for Japan and Indonesia. It was first described by Pierre André Latreille in 1804, though many of its species have been moved elsewhere. ...

''. In 2013, ''Tegenaria'' was split up, and the hobo spider was transferred to a new genus ''

Eratigena ''Eratigena'' is a genus of spider in the family Agelenidae. Most of its species were moved from the genus ''Tegenaria'' in 2013. Which is what this genus is named after, being an anagram of ''Tegenaria''. Two species that frequently build webs ...

'', an anagram of ''Tegenaria''.

Identification

Spiders, including the hobo spider, vary considerably in appearance, and identification can be difficult. The hobo spider is 7–14 mm in body length, and brownish in color. Identification relies on an examination of the spider’s anatomy. Like many species of spider the positive identification of ''Eratigena agrestis'' requires microscopic examination of the epigynum and

palpal bulb The two palpal bulbs – also known as palpal organs and genital bulbs – are the copulatory organs of a male spider. They are borne on the last segment of the pedipalps (the front "limbs" of a spider), giving the spider an appearance often descr ...

(the female and male sex organs respectively) and is best done by an

arachnologist Arachnology is the scientific study of arachnids, which comprise spiders and related invertebrates such as scorpions, pseudoscorpions, and harvestmen. Those who study spiders and other arachnids are arachnologists. More narrowly, the study of sp ...

. However, the following characteristics identify hobo spiders among other species with a similar general appearance: * Hobo spiders lack the colored bands found on many spiders of the family

Agelenidae The Agelenidae are a large family of spiders in the suborder Araneomorphae. Well-known examples include the common "grass spiders" of the genus ''Agelenopsis''. Nearly all Agelenidae are harmless to humans, but the bite of the hobo spider (''Erat ...

where the leg joints meet. * The abdomen has chevron (V-shaped) patterns (possibly many of them) down the middle, with the chevrons pointing towards the head. * Hobo spiders have a light stripe running down the middle of the sternum. If the spider instead has three or four pairs of light spots on the lateral portions of the sternum, then it is one of the other two related ''Eratigena'' species. However absence of spots is not conclusive proof that the spider is a hobo spider, since the spots on other ''Eratigena'' species may be extremely faint and not readily visible. * Hobo spiders do not have two distinct longitudinal dark stripes on the top side of the

cephalothorax The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...

, instead showing indistinct or diffused patterns. Washington spiders with distinct dark stripes include spiders from the genera ''Agelenopsis'' and ''Hololena'' and possibly some

wolf spiders Wolf spiders are members of the family Lycosidae (). They are robust and agile hunters with excellent eyesight. They live mostly in solitude, hunt alone, and do not spin webs. Some are opportunistic hunters, pouncing upon prey as they find it or ...

Distribution and habitat

''Eratigena agrestis'' is distributed from Europe to Central Asia, and is also found in western North America, in the

Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though ...

and

Great Basin The Great Basin is the largest area of contiguous endorheic basin, endorheic watersheds, those with no outlets, in North America. It spans nearly all of Nevada, much of Utah, and portions of California, Idaho, Oregon, Wyoming, and Baja California ...

. It is recorded in the checklist of Danish spider species, and is present on the small island of Peberholm, probably having been carried there by foreign trains. It is a resident of fields, avoiding human habitations occupied by major competitors, particularly the giant house spider (''Eratigena atrica''), which is a common resident of houses and other man-made structures in Europe. As a result, human contacts with the hobo spider are uncommon in Europe. Hobo spiders build a horizontal,

trampoline A trampoline is a device consisting of a piece of taut, strong fabric stretched between a steel frame using many coiled springs. Not all trampolines have springs, as the Springfree Trampoline uses glass-reinforced plastic rods. People bounce o ...

-like web near brick walls or wood piles where the spider has shelter and awaits prey.

Bite effects

Although the toxicity and aggression of the hobo spider have long been debated, there is little evidence that the hobo spider is a dangerously venomous species. The

CDC The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georgi ...

reported

case studies A case study is an in-depth, detailed examination of a particular case (or cases) within a real-world context. For example, case studies in medicine may focus on an individual patient or ailment; case studies in business might cover a particular fi ...

in the 1990s claiming that the hobo spider bite caused isolated cases of

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...

in people, but as of 2017, the CDC no longer lists the hobo spider among venomous species. In Canada, there is no evidence that hobo spider bites cause skin necrosis. Some bites reportedly from the closely related desert grass spider, '' Agelenopsis aperta,'' may have been inaccurately reported and may have actually been from the hobo spider.

References

Bibliography

* * * {{taxonbar, from=Q657085 Agelenidae Spiders of Europe Spiders of North America