The question of whether “Daddy Long Legs” make webs is complicated because this common name refers to two entirely different groups of arachnids. Determining the correct answer requires identifying which of the two common arachnids is being discussed, since their biological features and behaviors are fundamentally distinct. The difference lies in a deep evolutionary split that dictates whether the animal possesses the necessary biological machinery for silk production.
The Problem of Ambiguity
The common name “Daddy Long Legs” applies to two separate orders within the class Arachnida. One creature is the Harvestman (Order Opiliones), which is not a true spider. The other is the Cellar Spider (Family Pholcidae), which is a genuine spider in the Order Araneae. Both are recognizable by their extremely long, thin legs relative to their small body size, but their internal anatomy and life strategies are completely different. This ambiguity means that a simple “yes” or “no” answer to the question of web-spinning is insufficient without first identifying the species.
The Non-Web Spinners: Harvestmen (Opiliones)
Harvestmen are the arachnids most often referred to as “Daddy Long Legs” in many regions, and they do not produce silk or webs. Their classification in the Order Opiliones distinguishes them from true spiders, most notably by their body structure. Harvestmen possess a cephalothorax and abdomen that are broadly joined, appearing as a single, fused, oval segment without the distinct narrow waist seen in spiders. They lack the specialized silk-producing organs called spinnerets. Since they cannot produce silk, their hunting strategy relies on active searching or scavenging, rather than trapping prey. Harvestmen are omnivores, consuming small insects, plant matter, fungi, and decaying material, and they ingest solid food directly rather than liquefying it with venom.
The Web Spinners: Cellar Spiders (Pholcidae)
The second creature commonly called “Daddy Long Legs” is the Cellar Spider, a true spider and a prolific web-spinner. Cellar Spiders belong to the Family Pholcidae and are structurally distinct from Harvestmen, possessing two clear body segments connected by a narrow pedicel or “waist.” They are typically found in dark, damp environments such as basements and cellars, where they construct their traps. The webs they create are loose, irregular, and tangled structures often described as messy cobwebs, rather than geometrically precise orb-weaves. Cellar Spiders hang upside down in these webs, waiting for prey. When a vibration signals a trapped insect, they rapidly pulse or vibrate their bodies, shaking the web to further ensnare the prey. They continually layer new silk onto old webs, contributing to the thick, dusty appearance of their structures over time.
The Biological Function of Arachnid Silk
The ability to spin webs is directly linked to the presence of specialized structures called spinnerets, which are complex abdominal appendages unique to spiders. These spinnerets are connected to internal silk-producing glands that process a liquid protein solution into solid silk threads upon extrusion. Most spiders possess six spinnerets, though the number can vary, allowing them to produce different kinds of silk for various purposes. Spider silk is a strong, protein-based material that serves functions far beyond the creation of capture webs. Spiders use silk to construct protective egg sacs, to lay down a safety-line or dragline as they move, and for a dispersal method known as “ballooning,” where young spiderlings use a thread to catch the wind. The evolutionary divergence explains why Harvestmen do not spin: they lack the entire silk-producing apparatus, having evolved a strategy of active predation and scavenging, while true spiders developed the complex silk gland system as a primary tool for survival, reproduction, and hunting.