The common house spider (Parasteatoda tepidariorum), referred to internationally as the American house spider, is a spider species of the genus Parasteatoda that is mainly indigenous to the New World, with P. tepidariorum australis (common gray house spider) also encountered in some parts of Myanmar and Pakistan. American house spiders are synanthropic and build their tangled webs in or near human dwellings, often in secluded areas such as between loose walls and behind open doors and attic windows. Statistically, they are the most often encountered spider by humans in North America, and least likely to adopt defensive behavior in their vicinity. Their prey mechanism is similar to that of the other cobweb spiders: the spider follows disturbances transmitted along the web to entangle and then paralyze its prey, which usually consists of household insects and other invertebrates (often considered as pests).
American house spiders are generally dull brown in coloration, with patterns of differing shades often giving a vaguely spotted appearance (particularly noticeable on the legs). Their average body size is a quarter-inch (6 mm) long, but they can be an inch (2.5 cm) or more across with legs outspread. Their size and coloration allow the spiders to blend into the background and escape notice.
Like some other species of the family Theridiidae, P. tepidariorum is similar in body shape and size to widow spiders, which have venom that is classified as potentially dangerous.
This species can live for more than a year after reaching maturity. Each egg sac contains from 100 to more than 400 eggs, with a single female producing up to 17 egg sacs. The hatchlings remain in the mother's web for several days.
Diet and predation
American house spiders usually feed on small insects and household pests such as flies, mosquitoes, ants and wasps. They can randomly attack grasshoppers, butterflies, cockroaches or other spiders depending on their size. If the prey is too agile, the spider will try shooting web at it from a distance before pulling the thread toward itself. Bigger females can also attract baby skinks inside their web by leaving fly remains hanging in it. Once its food dries out, the spider usually drops it to the floor in order to free space in its web, instead of destroying and rebuilding it or changing its location.
Three spider species usually prey upon them: the pirate spiders of the genus Mimetus (Mimetidae), as well as two jumping spider species ‒ Phidippusvariegatus and Metacyrbaundata. The latter one also often falls prey to its own food when it gets trapped in the tangling web after missing the jump on its target.
The assassin bug Stenolemus lanipes (Emesinae) apparently feeds exclusively on spiderlings of this species, but can also become prey of the adult spider.
Interaction with other spiders
A male and female often share the same web for long periods, and several females often build their webs in close proximity. However, females will sometimes fight when they encounter each other.
Interaction with humans and predators
As these spiders live in constant proximity to humans, they are not usually aggressive and will even let a human hand approach their web. Like any other spider, however, they are afraid of bigger foes, and, in most cases, will retreat behind an obstacle (such as a dried leaf or prey remains) upon perceiving more than usual disturbance to their web. Further disturbance may lead to the spider dropping down on a thread, then running away from the web. If the distance is not considerable, it will usually return to its web within a couple of days. Otherwise, it will start a new one.
American house spiders possess poor vision and cannot detect any movement more than three to four inches away. If cornered, they will feign death as last resort.
Unlike most house spiders, which will wander the dwelling by spring if male, or seek refuge from the first cold by autumn if female, P. tepidariorum species of both sexes can be encountered in mid-winter, in wall corners or underneath the windowsill. Some species will build their webs there, other can remain almost motionless until prey is abundant.
American house spiders will bite humans only in self-defense, when grabbed and squeezed. Although the bite of this species is relative less severe compared to other theridiids, it has to be considered. Bites of P. tepidariorum can cause severe pain with a median duration of 16 hours, and in some cases systemic effects; which is very similar to the symptoms of steatodism (i.e. bites of false widows in the genus Steatoda).
Steatoda and Parasteatoda species can inflict bites with similar, but far less severe, painful symptoms to those of black widows. It is also powerful enough to kill the same species of spider on occasion. The synanthropic habits of several species may play a role in cases of human biting.
Similarly named species
The name "house spider" is also used worldwide of different spider species, notably Tegenaria domestica in Europe and Araneus cavaticus, also known as the barn spider. Many other species can be referred to as such; therefore it is preferable to use the scientific name for identification.
Hatched P. tepidariorum spiderlings
Female eating a Green Leafhopper (Cicadella viridis)
A male and female (the female is the larger of the two)
Closeup of a female P. tepidariorum
- ^ abFitch, Henry S. (1963). Spiders of The University of Kansas Natural History Reservation and Rockefeller Experimental Tract. [page needed]
- ^Hodge, Maggie (1984). "Anti-predator behavior of Achaearanea tepidariorum (Theridiidae) towards Stenolemus lanipes (Reduviidae): preliminary observations". Journal of Arachnology. 12 (3): 369–70. JSTOR 3705368.
- ^Faúndez, Eduardo I; Téllez, Fernando (2016). "New records for Parasteatoda tepidariorum (C.L. Koch, 1841) (Araneae: Theridiidae) in Southern Chile". Anales del Instituto de la Patagonia. 44 (3): 85–7. doi:10.4067/S0718-686X2016000300009.
- ^Garb, Jessica E; Hayashi, Cheryl Y (2013). "Molecular Evolution of α-Latrotoxin, the Exceptionally Potent Vertebrate Neurotoxin in Black Widow Spider Venom". Molecular Biology and Evolution. 30 (5): 999–1014. doi:10.1093/molbev/mst011. PMC 3670729. PMID 23339183.
- ^Faúndez, Eduardo I.; Téllez, Fernando (2016). "Consideraciones sobre Steatoda nobilis (Thorell, 1875) en Chile" [Considerations about Steatoda nobilis (Thorell, 1875) in Chile]. Biodiversity and Natural History (in Spanish). 2 (1): 13–5.
Achaearanea tepidariorum, the spider responsible for most cobwebs
House spiders range in color from a dirty white to almost black. The cephalothorax is yellow brown and the legs are light yellow with brown or gray rings at the ends and middle of the joints. The abdomen has six transverse black marks that curve upward; the marks are smaller and less defined in lighter-colored specimens.
Females range from 5 to 6 mm in length. Their first pair of legs are almost three times the length of the whole body. The legs are yellow. Males range from 3.8 to 4.7 mm in length. Their legs are noticeably longer in proportion to their body than those of the female, and are orange-brown in color.
Distribution and Habitat
The common house spider is found all over the world, although they are believed to be native to the neotropics.
This spider builds its large web in the corners of rooms, under furniture, in angles between fences, and between stones. It usually takes advantage of any space that provides the best "access" to the most prey.
The male and female may live together on the same web. The female lays her eggs in a brownish, pear-shaped egg sac that is 6 to 9 mm in diameter. Several batches of eggs may be laid in one season, and they simply hang in the web until hatching.
Habits and Behaviors
One part of the house spider's web is woven more closely than the rest of the web. This part is covered with an extra layer of silk, and it is in this part of the web that the spider stands in wait for its prey. When the web is constructed in an open space the spider may carry a small piece of leaf or other similar material into the web under which it hides.
The webs of young house spiders are much more regular than those of the adults.
The house spider's webs are made of sticky strands that catch dust and other debris as easily as prey. These webs are commonly found in houses and are what most people refer to as cobwebs.
A house spider catches its prey by waiting in the web until a large insect gets caught in the sticky threads. The spider then throws more silk onto its victim and pulls it up into the web. These spiders will change the sites of their webs if they are not catching enough prey.
family Theridiidae (cobweb spiders)
genus & species Achaearanea tepidariorum
Questions or comments about this page?