The common name “daddy long legs” causes significant confusion because it is applied to three distinct creatures across different regions, all of which have radically different diets. This ambiguity makes answering the simple question of whether they eat bugs complex. One creature is a highly effective predator, another is a harmless scavenger, and the third is primarily vegetarian. Understanding which creature is being discussed is the first step in determining its feeding habits.
The Identity Crisis: Clarifying the Three Creatures
The first group is the Harvestmen (order Opiliones), which are arachnids but not true spiders. Harvestmen are distinguished by their body structure, where the cephalothorax and abdomen are broadly fused into a single, oval segment. They possess only one pair of eyes, typically located centrally on a small mound called an ocularium.
The second group is the Cellar Spiders (family Pholcidae), which are true spiders. These arachnids have the characteristic spider body plan with two distinct segments: a separate cephalothorax and abdomen joined by a narrow stalk. Unlike Harvestmen, Cellar Spiders produce silk for webs and possess venom glands to subdue prey.
The third creature is the Crane Fly (family Tipulidae), a type of true fly. Crane Flies are recognized by their slender bodies, large size, and exceptionally fragile wings and legs. As insects, their bodies are divided into three parts: a head, thorax, and abdomen.
The Harvestman Diet (Opiliones): Scavengers and Omnivores
Harvestmen, the arachnids with the fused body, do not actively hunt and kill live insects like true spiders. They are opportunistic omnivores and scavengers, consuming a wide range of organic matter. They lack venom and have mouthparts capable of ingesting solid food particles, a distinct difference from most spiders.
Their diet includes dead or decaying insects, small soft-bodied invertebrates like aphids, and various types of vegetation and fungi. They play an important ecological role as decomposers, often feeding on bird droppings and other fecal material. While they consume small, slow-moving arthropods, they are not equipped to take down larger, active bugs.
Lacking silk glands, fangs, and venom, Harvestmen rely on finding their food rather than trapping it. They cannot immobilize prey with a bite; instead, they tear off small pieces of food and consume it. This makes them harmless to most live insects, and their primary contribution is cleaning up small detritus.
The Cellar Spider Diet (Pholcidae): True Predators
Cellar Spiders are definitive predators that actively eat other insects and spiders. They construct large, messy, three-dimensional webs that are not sticky but are complex enough to trap passing arthropods. Once an insect is entangled, the spider quickly runs to it, wraps it securely in silk, and delivers a venomous bite.
These spiders are effective hunters, capable of taking down prey far larger than themselves. They frequently consume household insects and small invertebrates, including ants and gnats. Their most famous habit is attacking and killing other spiders, often invading the webs of larger species like Black Widows.
They employ a specialized hunting technique by vibrating a neighboring spider’s web to mimic trapped prey, luring the host spider close enough for capture. This aggressive predation confirms that this type of “daddy long legs” is a successful bug-eater. The venom used to subdue prey is effective on small arthropods but poses no threat to humans.
The Crane Fly Diet (Tipulidae): Mostly Vegetarians
The Crane Fly is an insect whose diet is largely non-predatory, especially in its adult form. Adult Crane Flies have a short lifespan and often do not feed at all, focusing solely on reproduction. If they do consume anything, it is usually nectar or other sugary liquids, making them the most vegetarian of the three groups.
Their larvae, commonly known as leatherjackets, are the feeding stage. They primarily eat decaying organic matter in the soil or aquatic environments, consuming decomposing leaves, algae, and plant roots. They sometimes become minor pests in lawns by feeding on grass crowns.
While some aquatic species of Crane Fly larvae are predatory on other small aquatic invertebrates, the vast majority of terrestrial species are detritivores or herbivores. The adult Crane Fly does not eat other bugs and is harmless to humans.