The question of how long a house spider can live indoors has no single answer, as the term “house spider” refers to several different species with varying maximum lifespans. These arachnids thrive in the stable indoor environment of a home, which protects them from the elements and predators they would face outside. The longevity of any individual spider is determined by its specific species and the environmental conditions it encounters within your walls. This variability, which ranges from a few months to several years, depends on the common species and the factors that govern their survival indoors.
Common Species and Their Lifespan Range
The label “house spider” typically refers to two or three common types found in homes, each with a distinct life expectancy. The American House Spider (Parasteatoda tepidariorum), a common cobweb builder, has a relatively short lifespan, with females generally surviving for about one to two years. Males of this species often live for only a few months after reaching maturity, a pattern common across many spider types.
In contrast, the Cellar Spider (Pholcidae), often called a daddy long-legs spider, exhibits a notably longer lifespan, frequently surviving for two to three years indoors. Some individuals of this delicate-looking species have been known to live for up to five years under ideal, undisturbed conditions. The Giant House Spider (Eratigena atrica), or Barn Funnel Weaver, is one of the longest-lived house occupants, with an average life expectancy of two to three years, but undisturbed females can live for up to six or seven years.
This difference in lifespan is largely tied to gender, as female spiders consistently outlive males across almost all house-dwelling species. Females require sustained energy for producing multiple egg sacs and continue to feed throughout their adult lives. Males, conversely, are driven by a singular focus on reproduction and often stop eating entirely once they mature, making them more susceptible to exhaustion, predation, and natural death shortly after mating.
The Typical House Spider Life Cycle
The total lifespan of a house spider is the sum of its distinct biological phases: the egg, the juvenile stage, and the adult stage. The life clock begins when the female deposits her eggs in a silken sac, which can contain anywhere from a few dozen to several hundred eggs, depending on the species. The egg stage is relatively short, with spiderlings hatching inside the protective sac after an incubation period that usually lasts a few weeks.
Once the tiny spiderlings emerge, they enter the juvenile stage, which is the longest and most growth-intensive phase of their lives. During this time, the spider must repeatedly shed its hard outer shell, or exoskeleton, in a process known as molting. For many common house spiders, this growth period involves multiple molts, often between five and ten times, as the spider works toward its final adult size.
The juvenile stage can last for several months to a full year, with the final molt marking the transition to adulthood and reproductive capability. Most of the spider’s life is dedicated to growth and development, not spent as a fully mature adult. The adult stage, defined by the ability to reproduce, is often relatively brief for males but can last for years in females that continue to lay eggs.
Factors That Determine Longevity
While a species has a maximum potential lifespan, few individual house spiders reach this limit due to various external and environmental factors. The most immediate determinant of survival is the availability of prey, as a consistent supply of insects like flies and moths allows the spider to sustain its metabolic needs and successfully complete its molting cycles. A lack of food can halt growth and shorten a spider’s life, though they can often survive for weeks without a meal.
The indoor environment itself provides stability, which contributes greatly to longevity, particularly a consistent temperature that eliminates the threat of harsh outdoor winters. However, the specific humidity level is also important; cellar spiders, for example, thrive in damp areas like basements, while drier conditions can stress other species during the vulnerable molting process.
Predation poses a significant threat, even indoors, where spiders can fall victim to other indoor insects, such as centipedes, or household pets. Human intervention, whether through cleaning, vacuuming, or accidentally crushing the arachnid, is also a major factor that prevents most house spiders from living out their full natural lifespan.