Cellar spiders are common household arachnids, often raising concerns about their potential danger. This article clarifies facts about cellar spiders, addressing their characteristics, actual harmfulness, and how humans can coexist with them. Understanding these creatures can alleviate apprehension and highlight their role in indoor environments.
What Are Cellar Spiders
Cellar spiders, belonging to the family Pholcidae, are often called “daddy long-legs spiders.” This nickname also refers to harvestmen or crane flies, which are distinct arachnids or insects. These spiders typically have a body length of 7 to 8 millimeters, though their extremely long, thin legs can extend five to six times their body length, giving them a fragile and wispy appearance. Their bodies are oval-shaped and come in shades of pale yellowish, light brown, or gray. Like other spiders, they possess eight eyes, often arranged with two central eyes and three clustered on each side.
Cellar spiders commonly establish loose, irregular webs in dark, damp, and undisturbed indoor environments. Basements, cellars, attics, garages, and room corners are preferred habitats within human dwellings. They typically hang upside down in their webs, which are not sticky but rely on a complex matrix to ensnare prey.
Are Cellar Spiders Harmful
Cellar spiders possess venom, a characteristic shared by nearly all spiders. However, the common myth that their venom is highly potent but their fangs are too short to bite humans is largely unfounded. While their fangs are small, measuring around a quarter of a millimeter, they can penetrate human skin.
Scientific studies indicate that cellar spider venom is relatively mild and poses no medical danger to humans. If a bite were to occur, symptoms are typically minimal, such as a slight itch or mild redness, and medically significant reactions are extremely rare.
These spiders are generally non-aggressive and are unlikely to bite unless severely threatened or trapped. When disturbed, cellar spiders rapidly vibrate their webs, appearing as a blur to confuse predators. This behavior, combined with their reclusive nature, means interactions leading to a bite are infrequent.
Living Alongside Cellar Spiders
Cellar spiders play an ecological role within indoor environments, providing natural pest control. They prey on common household pests, including mosquitoes, gnats, flies, and moths. Notably, they also hunt and consume other spiders, even those larger than themselves, such as black widows and wolf spiders. Their presence can therefore help manage insect populations within a home.
Given their generally harmless nature and beneficial pest control activities, many people choose to coexist with cellar spiders. However, for those who prefer to manage their presence, several strategies can be employed. Reducing clutter in basements and other storage areas minimizes hiding spots. Sealing cracks and gaps around windows, doors, and foundations can prevent spiders from entering.
Controlling humidity levels in damp areas like basements with a dehumidifier can make the environment less appealing, as they thrive in moisture. Regularly removing existing webs, spiders, and egg sacs with a broom or vacuum is effective, as cellar spiders do not reuse their webs. Limiting other insect populations by removing food sources will also reduce the area’s attractiveness.