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common house spiders

Common House Spiders

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What Are Common House Spiders?

The common house spider, scientifically known as Parasteatoda tepidariorum, is a small and inconspicuous arachnid pest that is prevalent in many households across North America and Europe. These spiders are known by various common names, including the American house spider, the domestic house spider, and the cobweb spider. Here is an overview of the common house spider:

  • Taxonomy and Classification: Parasteatoda tepidariorum belongs to the family Theridiidae, which includes cobweb or tangle-web spiders. The Theridiidae family is characterized by its unique ability to construct irregular three-dimensional webs with sticky silk for catching prey.

  • Physical Characteristics: Common house spiders are relatively small, with a body length ranging from 4 to 9 millimeters. They typically have a light brown to tan cephalothorax (front part) and a yellowish-brown to dark brown abdomen, sometimes featuring a geometric pattern on their dorsal side. The abdomen is usually spherical in shape.

  • Habitat and Distribution: Common house spiders are highly adaptable and are frequently found in and around human dwellings. They are often discovered in corners, crevices, and other concealed areas. These spiders are distributed widely across North America and Europe, and they can thrive in a variety of climates.

  • Web Construction and Behavior: Parasteatoda tepidariorum constructs tangled, irregular webs that are commonly located in corners, near windows, or in other sheltered spots. They are not known for actively hunting but rather passively waiting for prey to become entangled in their web. When vibrations indicate a potential meal, they will quickly rush to immobilize their prey using silk.

  • Diet: Common house spiders feed on a variety of small insects that become ensnared in their webs. Their diet may include flies, mosquitoes, ants, and other tiny arthropods.

  • Reproduction: These spiders reproduce through sexual reproduction. Males usually initiate courtship by vibrating their webs, and when they successfully approach a female, they deposit sperm. After mating, females lay their eggs in a silken sac, which they protect and guard. The young spiders hatch from the sac and disperse when they reach a certain size.

  • Venom: The venom of Parasteatoda tepidariorum is not considered medically significant to humans. While they do possess venom glands and can deliver venom to subdue their prey, their bites are rarely felt by humans, and any resulting effects are typically limited to localized pain, redness, or swelling.

  • Ecosystem Role: Common house spiders play a valuable ecological role in controlling insect populations within human habitats. By capturing and consuming a variety of pests, they can help reduce the need for chemical pest control.

The common house spider, Parasteatoda tepidariorum, is a small, inconspicuous spider that is commonly found in and around human dwellings. Their unique webs and passive hunting behavior make them effective at catching small insects. While they have venom, their bites are generally harmless to humans, and they contribute to pest control in the ecosystem.

What Do Common House Spiders Look Like?

The common house spider (Parasteatoda tepidariorum) is a relatively small arachnid with distinct physical characteristics. Here is a detailed description of their appearance:

  • Size: Common house spiders are typically quite small, with an adult body length ranging from 4 to 9 millimeters (0.16 to 0.35 inches).
  • Coloration: Their coloration can vary, but they often have the following features: The front part of the spider, called the cephalothorax, is usually light brown to tan in color. The abdomen, which is the posterior part of the spider, tends to be yellowish-brown to dark brown. It can have a mottled or geometric pattern on its dorsal side, which may appear as a series of chevrons or bands.
  • Abdomen Shape: The abdomen of the common house spider is typically rounded or somewhat spherical, giving the spider a compact appearance.
  • Legs: They have eight long, thin legs, which are covered in fine hairs. The legs are often a similar color to the cephalothorax.
  • Eyes: These spiders have eight eyes arranged in two rows. The eyes are usually small and not very prominent.
  • Spinnerets: At the rear of the abdomen, house spiders have spinnerets, which are specialized silk-spinning structures. These spinnerets are used to create their characteristic cobwebs.

Common house spiders are small arachnids with a compact body. They typically have a light brown to tan cephalothorax and a yellowish to dark brown abdomen, often with distinctive patterns. Their long, slender legs and the spinnerets at the rear of their abdomen are notable features of their appearance.

Where Are Common House Spiders Found?

Common house spiders (Parasteatoda tepidariorum) are highly adaptable arachnids that can be found in and around human dwellings. They are frequently encountered in a variety of indoor and outdoor locations. Here is a comprehensive list of places where you might find these spiders:

Indoor Locations:

  • Corners: Common house spiders are known for building irregular webs in corners of rooms, especially near ceilings.
  • Windows: They often construct webs around window frames and sills.
  • Attics and Basements: These spiders can be found in attics and basements, where they seek refuge and establish webs in hidden areas.
  • Closets: Dark, undisturbed closets may also be home to house spiders.
  • Sheds and Garages: In storage spaces, you may find them in corners and along the walls.
  • Bathrooms: They can occasionally be found in bathrooms, often near fixtures and corners.
  • Cellars: House spiders may inhabit cellars and crawl spaces.

Outdoor Locations:

  • Exterior Walls: Common house spiders sometimes construct webs on the exterior walls of buildings.
  • Garden Sheds: These spiders may also be found in garden sheds, where they build webs in secluded corners.
  • Fences: Outdoor fences can also host their webs, especially in less trafficked areas.
  • Vegetation: House spiders may be present in gardens, particularly in dense vegetation and among plants.

Hiding Spots:

  • Cracks and Crevices: These spiders are adept at finding and occupying small cracks and crevices in walls, furniture, and other structures.
  • Sheltered Areas: House spiders prefer sheltered and less disturbed locations, so they are often found in areas where they are less likely to be disturbed by human activity.

Common house spiders are opportunistic and will build their webs in areas where prey is likely to be abundant. Their ability to adapt to indoor and outdoor environments makes them a common presence in many households and buildings. While they are not dangerous to humans, they play a valuable role in controlling insect populations by capturing and consuming various pests that venture into their webs.

What Is The Life Cycle Of Common House Spiders?

The life cycle of common house spiders (Parasteatoda tepidariorum) includes several stages from birth to adulthood. Here is an overview of their life cycle:

Egg Stage:

  • The life cycle begins when the adult female spider lays her eggs. These eggs are usually encased in a silken sac, which she attaches to a web or another suitable surface.
  • The female guards the egg sac, protecting it from predators and environmental factors.

Spiderling Stage:

  • After an incubation period, spiderlings hatch from the egg sac. They emerge as tiny, immature spiders.
  • At this stage, spiderlings resemble miniature versions of adult house spiders but lack the distinctive markings and coloration.

Juvenile Stage:

  • As spiderlings grow, they go through multiple molts or shedding of their exoskeleton to accommodate their increasing size.
  • With each molt, they gradually develop adult characteristics, including the species-specific coloration.

Subadult Stage:

  • Subadult spiders are larger than spiderlings and have developed more of the physical features seen in adult house spiders.
  • They continue to feed, grow, and mature.

Adult Stage:

  • Once a spider reaches full maturity, it enters the adult stage. This stage is marked by the ability to reproduce.
  • Adult males and females differ in size, with females typically being larger.
  • Mating occurs, and females produce egg sacs to continue the life cycle.


  • Mating typically involves the male spider initiating courtship, often by vibrating the female's web.
  • Once mating is successful, the female will produce one or more egg sacs, each containing a large number of eggs.
  • The female guards the egg sac and may stay with it until the spiderlings hatch.


  • The lifespan of a common house spider can vary, but it is typically about one to two years.
  • The exact duration of each life stage, from egg to adult, can vary depending on environmental conditions, food availability, and other factors.


  • After hatching from the egg sac, spiderlings disperse by releasing silk threads into the air, a behavior known as "ballooning." This allows them to be carried by the wind to new locations, helping them establish in different areas.

The life cycle of common house spiders is characterized by gradual growth, molting, and reproductive activity. These spiders reproduce through sexual reproduction, with females being responsible for egg production and care. As they continue to reproduce and disperse, house spiders play a role in maintaining their population in various environments, including human habitats.

What Do Common House Spiders Eat?

Common house spiders (Parasteatoda tepidariorum) are opportunistic predators and consume a variety of small insects and arthropods that become ensnared in their webs. Their diet primarily consists of:

  • Flying Insects: House spiders often capture and feed on flying insects such as flies, mosquitoes, moths, and small winged ants.

  • Crawling Insects: They also consume crawling insects, including ants, beetles, and small roaches, which may inadvertently wander into their webs.

  • Other Spiders: Common house spiders may engage in cannibalism and prey on smaller or weaker spiders, including other members of their own species.

  • Non-Insect Prey: While insects are their primary prey, house spiders can also catch non-insect arthropods like small spiders, springtails, and other tiny creatures that end up in their webs.

  • Prey Entrapped in Webs: Their diet mainly consists of prey items that become ensnared in their cobwebs. They immobilize their prey by wrapping it in silk and deliver digestive enzymes to break down the prey's body, making it easier to consume.

Common house spiders play a beneficial role in controlling insect populations within their habitat. By capturing and consuming various pests, they can help reduce the number of unwanted insects in and around homes. While they are not dangerous to humans and are generally considered harmless, they contribute to natural pest control and are a valuable part of the ecosystem.

Are Common House Spiders Dangerous?

Common house spiders (Parasteatoda tepidariorum) are not considered dangerous to humans. They are generally harmless and pose no significant threat. Here are some reasons why they are not dangerous:

  • Venom: While common house spiders do possess venom glands and can deliver venom to subdue their prey, their venom is not potent enough to cause harm to humans. Their bites are typically too mild to be felt or may result in localized pain, redness, or swelling, similar to a mild bee sting.
  • Non-Aggressive: House spiders are not aggressive toward humans. They are more likely to retreat or hide when they sense human presence rather than bite in defense.
  • Rare Bites: Bites from common house spiders are infrequent because they prefer to avoid human contact. Bites generally occur when a spider is accidentally squeezed or feels threatened.
  • Health Risks: Unlike some other spiders, common house spiders are not known to transmit diseases or cause allergic reactions in humans.
  • Beneficial Predators: These spiders play a valuable role in pest control by capturing and consuming small insects in and around homes. Their presence can actually be beneficial by helping to reduce the population of unwanted pests.

Common house spiders are not dangerous to humans. While they may bite if they feel threatened, the resulting effects are typically mild and temporary. These spiders are more of a nuisance to pests and are considered beneficial in helping to keep insect populations in check within human habitats.

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