The common term “granddaddy long legs” causes frequent confusion because it refers to two distinct arachnids that often invade homes: the harmless Opiliones (harvestman) and the true spider Pholcidae (cellar spider). Both creatures are generally harmless to humans and pets, but their presence indoors can be unwelcome. Understanding which creature you are dealing with is the first step toward effective removal and long-term prevention. This guide offers practical steps for identifying and managing these visitors.
Identifying the Culprit
The harvestman (Opiliones) is not a true spider; its cephalothorax and abdomen are fused, giving it the appearance of a single, oval body segment. Harvestmen do not produce silk or webs. They possess chewing mouthparts rather than fangs, making them incapable of producing venom or biting humans. They are scavengers, often found outdoors or in damp, dark areas like basements.
The cellar spider (Pholcidae) is a true spider and a predator, possessing the distinct two-body-segment structure typical of spiders. These arachnids are easily identified by the messy, irregular webs they weave in corners of ceilings and windows. Although cellar spiders possess venom and fangs, the fangs are too small to penetrate human skin, making them medically insignificant. Their presence indoors usually indicates a food source, as they prey on other insects and other spiders.
Immediate Physical Removal Techniques
For creatures already inside the home, physical removal is the most direct solution. Vacuuming is an effective method for dealing with both types of arachnids, especially the cellar spider and its extensive webbing. Use a vacuum cleaner with a hose attachment to quickly remove the spiders, their webs, and any egg sacs. Immediately dispose of the vacuum contents outdoors in a sealed bag to prevent the creatures from escaping back into the house.
For individual harvestmen, safe capture and release is a humane method. Place a glass cup over the arachnid and slide a stiff piece of paper or cardboard underneath to trap it. The creature can then be safely carried outside and released far from the home’s foundation. This method is suitable for the harvestman.
Sticky traps, also known as glue boards, are a passive removal technique for both harvestmen and cellar spiders. Place these traps along baseboards, in dark corners, and near known entry points. They are useful in areas where the creatures travel or hide but are less effective for catching cellar spiders suspended in their webs. Regularly check and discard these traps, as they indicate the location of the highest activity.
Disrupting established habitats is necessary, particularly for cellar spiders. Use a long-handled brush or duster to sweep down the cobwebs they construct in ceiling corners and under furniture. Removing the webs and any attached egg sacs prevents future generations from populating the area. This destruction of their shelter forces existing spiders to move elsewhere.
Structural and Environmental Prevention
Long-term control relies on making the indoor environment inhospitable and inaccessible. Structural exclusion is a primary step, focusing on sealing all potential entry points into the home. Use high-quality silicone caulk to close gaps around window frames, door jambs, and foundation cracks. Pay particular attention to utility lines, such as electrical conduits and plumbing pipes, where they enter the structure, as these are common access points.
Both the harvestman and the cellar spider are drawn to areas of high humidity. Addressing moisture issues is paramount for effective prevention, as it removes a major environmental attractant. Install dehumidifiers in damp areas like basements and crawl spaces, aiming to maintain a relative humidity level below 50%. This lower moisture content significantly reduces their ability to hydrate and reproduce.
Fixing leaky plumbing and ensuring proper ventilation in bathrooms and attics also reduces ambient moisture. When the air is drier, it becomes more difficult for the creatures to survive. This environmental change makes the home less appealing than the outdoors.
Reducing the availability of a food supply further discourages cellar spiders. Cellar spiders feed on a variety of household pests, including silverfish and flies, which are often attracted by moisture. Controlling the general insect population through cleanliness and moisture management cuts off the spiders’ primary food source. Removing clutter, especially in storage areas, also eliminates the dark, protected hiding spots that both harvestmen and cellar spiders prefer.