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Tegenaria agrestis

By Joshua Price

Geographic Range

Hobo spiders are native to western Europe and were introduced to the Pacific Northwest region of the United States (accidentally, most likely through the Port of Seattle) as well as southern portions of British Columbia, sometime before the 1930s. This spider has since spread as far south as Nevada and as far east as Montana and Wyoming. (Baird and Stoltz, 2002; Davis, 2012; Schalau, 2007; Vest, 1999; Vetter and Roe, 203)

Habitat

Native European populations of hobo spiders prefer to nest outdoors and typically do not live near humans. North American populations, however, are regularly found nesting near humans, often near, and sometimes in, houses. They also nest under rocks and other objects in yards or gardens. Recently, hobo spiders have been found nesting in rural habitats in the United States. (Crawford, 2008; Schalau, 2007; Vest, 1999)

Physical Description

Hobo spiders have long legs (a characteristic of funnel-web spiders), which have fine hairs and are uniform in color. They usually have a brown cephalothorax with diffuse, indistinct darker brown markings on the legs and abdomen. The underside of the abdomen has a characteristic yellow marking with no spots, distinguishing it from other Tegenaria species. Male hobo spiders share the enlarged pedipalps found in many other spider species; examination of male pedipalps and female epigynum, requiring magnification, is required for sexual identification. Physical variation among individuals tends to be quite high, with a large range of colors and sizes recorded. Size ranges from 6-18 mm with an average length of 12 mm. Females are typically larger than males. (Crawford, 2008; Schalau, 2007; Vetter and Antonelli, 2002; Vetter and Antonelli, 2012; Vetter, 2006)

  • Sexual Dimorphism
  • female larger
  • Range length
    6 to 18 mm
    0.24 to 0.71 in

Development

Hobo spider eggs hatch in late spring to early summer, having been laid the previous fall. This species has three distinct stages of life with molting occurring between each stage: small juvenile, medium-sized immature and adult. Lifespan is greatly influenced by climate, with warmer, coastal populations completing their life cycle in a year and inland populations tending to follow a three year life cycle. (Crawford, 2008; Schalau, 2007; Vest, 1999)

Reproduction

Males use their pedipalps to insert sperm into the female’s epigynum where fertilization takes place. Males die shortly after mating and females die shortly after laying egg cases. It is reasonable to assume that only one mate is taken in the life-span of the spider as members of the species die shortly after breeding. (Crawford, 2008; Schalau, 2007; Vetter and Antonelli, 2002)

Mating takes place in late summer to early fall. Females are largely stationary in the web while males wander in search of mates. Females produce one to four egg cases, each of which can contain 100 or more eggs. The egg cases are deposited and attached to the undersides of rocks, wood, or other structures and are composed of layers of silk mixed with dirt and debris. After eggs are laid, the female usually dies, though there are some cases of females overwintering into another breeding season. Eggs gestate through the winter, hatching the following year. (Crawford, 2008; Schalau, 2007; Vest, 1999)

  • Breeding interval
    Once in life-span (1-3 years)
  • Breeding season
    Mid-July to August
  • Range number of offspring
    100 to 400
  • Average gestation period
    6 months
  • Range age at sexual or reproductive maturity (female)
    3 to 36 months
  • Range age at sexual or reproductive maturity (male)
    3 to 36 months

Males provide no parental investment after copulation. Females place egg cases in secure spots after laying but usually die before hatching takes place. (Crawford, 2008; Schalau, 2007)

  • Parental Investment
  • no parental involvement
  • precocial

Lifespan/Longevity

Populations of hobo spiders found in coastal or warmer climates have a life cycle averaging one year. Inland populations tend to be more long-lived, with a lifespan of up to three years. Most individuals die shortly after mating, however females occasionally live through the winter after mating. (Crawford, 2008; Schalau, 2007)

  • Typical lifespan
    Status: wild
    1 to 3 years

Behavior

Hobo spiders are solitary creatures, preferring to live in dark places (under rocks and other debris) or occasionally in homes or under foundations. Like many other funnel-web spiders, they make a web with a large flat surface tapering to a funnel where the spider sits in wait for prey. The web's construction, consisting of overlapping strands of silk (rather than stickiness as with most other spider webs), causes prey to become entangled, at which point the spider exits the funnel quickly and captures it. This species' scientific name translates to "agressive house spider" although it has been found to be no more aggressive than other spider species. Hobo spiders do bite when provoked, but it is a common myth that they will bite or attack without provocation. (Crawford, 2008; Schalau, 2007; Vest, 1999)

Home Range

Individuals typically stay within the small range of their webs, but will occasionally wander in search of a better location. Males leave their webs to search for mates during breeding season. (Crawford, 2008)

Communication and Perception

These spiders perceive their environments using three main receptors: mechanoreceptors, chemoreceptors, and photoreceptors. Mechanoreceptors are the most important sensory channel and consist of a number of very sensitive hairs located on the legs. The legs also house a number of sensilla that detect small air pressure changes. Chemoreceptors can also be found in hairs, usually on the legs and pedipalps, and are known as "taste hairs". These hairs are used to detect prey suitability as well as during courtship when males uses these receptors to follow pheromones laid down by females. Photoreceptors are found in the eyes of spiders, providing them with basic visual information, though images are unfocused due to the small size of their lenses. (Foelix, 1982)

Food Habits

Hobo spiders prey on any insect species that becomes tangled in their webs. No information regarding specific prey is available at this time. (Binford, 2000; Crawford, 2008; Vetter, 2006)

  • Animal Foods
  • insects

Predation

Insects such as praying mantises and black and yellow dauber wasps, as well as other spider species such as flower crab spiders, giant house spiders and American house spiders are known to prey on hobo spiders. (Crawford, 2008; Vest, 1999)

  • Known Predators
    • American house spider (Achaearanea tepidariorum)
    • Praying mantis (Mantis religiosa)
    • Flower crab spider (Misumena vatia)
    • Black and yellow dauber wasp (Scelifron caementarium)
    • Giant house spider (Tegenaria gigantea)

Ecosystem Roles

Hobo spiders prey on small to moderate sized insects such as ants, beetles, and flies that are caught in their webs (often located inside houses, under rocks, or sometimes in clumps of grass outdoors), controlling the populations of these species. Hobo spiders are themselves prey, particularly for giant house spiders, with lower population sizes of the first significantly correlated to higher populations of the second. Food competitors include crab spiders (Philodromus and Xysticus sp.), wolf spiders (Pardosa sp.), and other web-building spiders, including orb web weavers (Family Araneidae). There is currently no information available regarding parasites of hobo spiders. (Binford, 2000; Crawford, 2008; Vest, 1999)

Economic Importance for Humans: Positive

Since hobo spiders often live near or inside houses, they can often aid in getting rid of pest insects that share the same habitat. (Binford, 2000)

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

There is great debate as to the toxicity of hobo spider venom to humans. Venom of the North American populations of this species has been suspected to cause fairly severe necrotic wounds (necrotic araneism) at injection sites, with some evidence that the venom causes comparable effects to that of brown recluse spiders, while European populations have not been considered to be dangerously venomous to humans. This species is notoriously difficult to identify, however, and some recent studies indicate that the necrotic effects attributable to hobo spider venom represent a case of mistaken identity. ("Necrotic Arachnidism -- Pacific Northwest, 1988-1996", 2001; Bennett and Vetter, 2004; Crawford, 2008; Vest, 1999; Vetter, 2006)

  • Negative Impacts
  • injures humans
  • household pest

Conservation Status

This species is not listed in any database as being endangered or having any special conservation status.

Contributors

Joshua Price (author), University of Michigan-Ann Arbor, Jeremy Wright (editor), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

insectivore

An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

semelparous

offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

venomous

an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

2001. "Necrotic Arachnidism -- Pacific Northwest, 1988-1996" (On-line). Accessed February 01, 2012 at http://www.cdc.gov/mmwr/preview/mmwrhtml/00042059.htm.

Baird, C., R. Stoltz. 2002. Range Expansion of the Hobo Spider, Tegenaria Agrestis, in the Northwestern United States (Aranae, Agelenidae). Journal of Arachnology, 30/2: 202-204. Accessed February 01, 2012 at http://dl2af5jf3e.search.serialssolutions.com/?ctx_ver=Z39.88-2004&ctx_enc=info%3Aofi%2Fenc%3AUTF-8&rfr_id=info:sid/summon.serialssolutions.com&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.genre=article&rft.atitle=RANGE+EXPANSION+OF+THE+HOBO+SPIDER%2C+TEGENARIA+AGRESTIS%2C+IN+THE+NORTHWESTERN+UNITED+STATES+%28ARANEAE%2C+AGELENIDAE%29&rft.jtitle=Journal+of+Arachnology&rft.au=Baird%2C+Craig+R&rft.au=Stoltz%2C+Robert+L&rft.date=2002-08-01&rft.issn=0161-8202&rft.volume=30&rft.issue=2&rft.spage=201&rft.epage=204&rft_id=info:doi/10.1636%2F0161-8202%282002%29030%5B0201%3AREOTHS%5D2.0.CO%3B2&rft.externalDBID=n%2Fa&rft.externalDocID=10_1636_0161_8202_2002_030_0201_REOTHS_2_0_CO_2.

Bennett, R., R. Vetter. 2004. An approach to spider bites. Erroneous attribution of dermonecrotic lesions to brown recluse or hobo spider bites in Canada.. Can Fam Physician, 50/1: 1098-1101. Accessed February 02, 2012 at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2214648/.

Binford, G. 2000. An analysis of geographic and intersexual chemical variation in venoms of the spider Tegenaria agrestis (Agelenidae). Toxicon, 39/1: 955-968. Accessed February 03, 2012 at http://legacy.lclark.edu/~binford/Toxicon2001.pdf.

Crawford, R. 2008. "Hobo Spider" (On-line). Accessed February 01, 2012 at http://www.fs.fed.us/r1/fire/nrcg/Committees/Operations/ims/ims_web_site/Hobo%20Spider.htm.

Davis, R. 2012. "Hobo Spiders (Tegenaria agrestis)" (On-line). Accessed February 03, 2012 at http://utahpests.usu.edu/uppdl/htm/hobo-spiders/.

Foelix, R. 1982. Biology of Spiders. Cambridge, Massachusetts and London, England: Harvard University Press.

Schalau, J. 2007. "Backyard Gardner" (On-line). Accessed February 03, 2012 at http://ag.arizona.edu/yavapai/anr/hort/byg/archive/hobospiders.html.

Vest, D. 1999. "The Hobo Spider Website" (On-line). Accessed September 06, 2012 at http://hobospider.org/.

Vetter, R. 2006. "Hobo Spider Management Guide" (On-line). Accessed February 02, 2012 at http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7488.html.

Vetter, R., A. Roe. 203. Distribution of the Medically-implicated Hobo Spider (Araneae: Agelenidae) and a Benign Congener, Tegenaria duellica, in the United States and Canada. Journal of Medical Entomology, 40/2: 159-164. Accessed February 03, 2012 at http://www.geog.ubc.ca/biodiversity/efauna/documents/hobo_spiders.pdf.

Vetter, R., A. Antonelli. 2002. "How to identify (or misidentify) the hobo spider" (On-line). Accessed February 03, 2012 at http://pep.wsu.edu/pdf/PLS116_1.pdf.

Vetter, R., A. Antonelli. 2012. "How to identify (or misidentify) the hobo spider" (On-line). Accessed September 06, 2012 at http://pep.wsu.edu/pdf/PLS116_1.pdf.

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