The term “daddy long legs” often causes confusion, as it commonly refers to several distinct arthropods. While some use it to describe crane flies, this article focuses on the arachnid types most frequently found in homes: harvestmen and cellar spiders. Understanding the specific factors that draw these creatures indoors can help clarify their presence.
Understanding Daddy Long Legs Species
The arachnids commonly called “daddy long legs” include harvestmen (Order Opiliones) and cellar spiders (family Pholcidae). Harvestmen have a single, fused body segment and, unlike true spiders, lack venom glands and silk-producing spinnerets, so they do not spin webs.
Cellar spiders are true spiders with two distinct body segments (cephalothorax and abdomen) and spin messy, tangled webs. Though cellar spiders have fangs and venom glands, their venom is too weak to harm humans, and their fangs are often too short to penetrate human skin. Both types are largely harmless to humans.
Preferred Environmental Conditions
These arachnids are drawn to environments that offer specific conditions for their survival. Humidity and dampness are attractive, as moisture helps prevent desiccation for both harvestmen and cellar spiders. Basements, crawl spaces, and garages often provide the necessary moisture levels. They also prefer dark and secluded locations, such as undisturbed corners, crevices, or spaces behind furniture, where they can hide. Dim lighting helps them avoid predators and carry out their activities without disruption.
Temperature also plays a role in their habitat selection. Both harvestmen and cellar spiders favor moderate to cool temperatures, avoiding extremes of heat or cold. Many harvestmen are nocturnal, seeking shelter from the sun during the day in cool, shaded spots. Undisturbed spaces with minimal human traffic are appealing, providing a sense of security and allowing them to establish themselves without frequent disruption. These conditions collectively create an ideal habitat that mimics their natural outdoor preferences, making certain indoor areas inviting.
Prey and Food Sources
The availability of food is a primary factor attracting these arachnids. Harvestmen have a diverse diet, often acting as omnivores or scavengers. They consume small insects, decaying plant matter, fungi, and other dead arthropods. Some species prey on aphids, slugs, mites, and beetle larvae. They ingest small solid particles of their food rather than sucking liquids.
Cellar spiders are predatory, hunting other spiders and small insects like mosquitoes, gnats, moths, and flies. They can prey on insects and spiders much larger than themselves, including large house spiders or black widow spiders. Cellar spiders use their webs to trap prey, then rapidly shake the web to entangle their meal before consuming it. The presence of common household pests, which serve as prey, indirectly attracts cellar spiders indoors. A consistent food supply makes a location a desirable habitat.
Indoor Habitats and Entry
Indoor environments often resemble the preferred habitats of harvestmen and cellar spiders, drawing them inside. Basements, attics, crawl spaces, and garages are common indoor locations for both arachnid types. These areas provide the necessary humidity, darkness, and undisturbed conditions. Cellar spiders often spin loose, messy webs in room corners or ceilings, benefiting from stable indoor temperatures.
These arachnids gain access through various small openings. Cracks in foundations or walls, gaps around windows and doors, and open windows or doors serve as entry points. They can also be inadvertently carried inside on items brought into the home. Accessible entry points make human dwellings readily available and attractive environments for both.